The way to get traffic is to have quality inbound links to your websites. If your site has original and interesting content, you don't have to do anything, The links will find you. The spiders will cover your site and gobble up your valuable keywords and spit them out as good placement in the search engines.
There are some purely mechanical things that you can do to increase inbound links. There are various ways to manipulate the web to get traffic, but I have found that link farms, pay-for-links, and free-for-all links are useless and can even have a negative impact. Getting quality links is an art. Here are a few things that I've be using that work for me.

Natural Links:
These are links from other websites that you deserve to get. You have content that some webmaster thinks is important. These would be mentions in blogs, forum postings, or from the links pages of sites similar to yours. These are the best links. People click these links and Google places a high value on these links. These are the links that you want.
If your are a resource, you can get listed in resource sites (like Ralans and SpiceyGreenIguana if you are a spec-fic publisher). If they haven’t listed your site, suggest that that they should. If you have a zine, getting all of your writers to link back to you from their home pages is a good idea. Ask them to link to the website main page a well as individual articles.
You can write for other websites and make sure that they include a link to your home page at the end of the article or story.

Link Exchanges:
You can contact other websites like yours and ask for reciprocal links. You should have a links page where you add all of your friendly competitors and then they can create a similar page with a link back to you. This is less effective than natural links, because Google takes away a little Mojo from interlocking links. The idea is that the links have less value if you are patting the back of the guy who is patting your back. The clicks that you get directly from these are good surfers who will bookmark your site and come back for more.

Webrings:
Webrings are interlocking links of similar websites. There are webrings for most everything and most of my sites belong to at least one webring. I have even started a Spec Fic Bloggers webring. The links in webrings are JavaScript so that Google can't see them, but Google spiders the webring's home sites and a link from a webring site is good link. Most webrings are moderated and good ringmasters don't allow off topic websites to sneak into their rings. Join a few webrings or start one of your own at webring.com.

Blog Carnivals:
I just found out about these. A blog carnival is a regular blog consisting of links to other people's blog entries. It is a blog of blogs. The idea is that people use blog carnivals to read about tightly focused subjects written by a variety of authors. Most Blog Carnivals have tools where bloggers can suggest their blog entries to the blog carnival blogmaster. These are good links. I have been trying them out on a few specific subjects. I am also working on some tools and I will create a few blog carnivals of my own. I am guessing that Google spiders these and gives appropriate weight to the link. I did notice a modest increase in traffic coming from them and I will keep testing.
From now on, whenever I make a blog entry that I think might have some general appeal, I am going out to the blog carnival sites and see if I can submit the link somewhere. This article, longer than I usually write, was designed to check out the blog carnivals to see how well they work.

DMOZ:
A listing in DMOZ.org is at the heart of getting hits from search engines. Almost all of the search engines pull their default description of your site from DMOZ. If it can't find it on DMOZ it uses the description meta tag in your web pages and if it can't find that it grabs some random words from your web page. A listing in DMOZ guarantees that you get a decent place in the search engines (not just Google) when people look for specific data on your site.
An entry in DMOZ is a very good thing for traffic, even if the traffic doesn't come directly from DMOZ.
Similar to DMOZ is the Librarians Internet Index, LII.org. This is a harder to get in than DMOZ, but every search engine takes the sites listed in LII seriously.

RSS Aggregators:
If your site doesn't have an RSS feed (most blogs do), see if you can create one. Keep it updated when you make changes to your site. Register it with FeedBurner.com and some other RSS Feed Aggregators. Every website needs a feed even it hardly ever changes. There is a whole world out there that doesn't surf, the web, they surf RSS. Get yourself listed and you can tap into these RSS-ers. The Aggregators create a good deal of traffic and it is good quality traffic consisting of readers who will keep coming back.

Digg, Del.icio.us and other bookmark sites:
Digg.com lets you put a little icon which allows surfers to rate your site. Del.icio.us is bookmark service. StumbleUpon.com lets users look at sites that they are likely to enjoy based on their surfing history. These sites produce quite a bit of traffic because they are a compilation of human opinions and not the result of an algorithm. Getting Digged (Dugg?) or bookmarked in Del.icio.us or getting a positive rating in Stumbleupon produces a steady flow of traffic. Register with all of these and put the icons on your site.

Writing Free Articles:
If you have a specific skill you should write about it. You need to create articles from 500 to 2000 words that you don't mind giving away free. There are a variety of sites that will offer these articles to the public. Websites that need content will then either buy them (you might even get a royalty payment) or most likely use them with a link back to the author. The link back is often more important than a few pennies royalty.
I haven't used this, but I understand that an good article can be worth a few hundred back links.
Very technical articles with MBA action keywords like Managing, Publishing, Programming, Installing, Creating, Coping, and Generating, seem to be the ones that people want. (don’t forget Free!)

Google Sitemaps:
Create a sitemap of your site and register it with Google Sitemaps. This almost guarantees your web pages get listed in Google almost as soon as you create them. I suspect that a site with a good sitemap has a good chance of getting links from Google.

Google Adsense:
I suspect that a site with Adsense ads has more inbound clicks from Google than a page with no ads on it. Google makes money by directing people to a site with Adsense ads on it – it would be logical if they gave the Adsense ads preference. Google denies this, but I don't believe them.
You're crazy if you don't have Adsense ads on your site anyway. It's free money. There is also some evidence that your site is spidered faster if you have adsense ads.

Google Adwords:
If you want to pay for clicks, use Adwords or possibly Yahoo Publisher Network (YPN). You can pay as little as a nickel per click and budget yourself so that you don't have to pay much a month. Clicks coming in through these ads are often good clicks from potential new friends who will bookmark your site and stop by again.
I only use Adwords for websites where I sell something. I can see traffic coming in and I use Google Analytics to see if it pays and so far, it always has.

Shelf Space:
Use lots of pages. Divide long pages into multiple linked pages. An ideal page has 250 to 500 words of good content (not counting links, ads and repeated information). If you have one website that covers a variety of subjects, break it up and spread it out over different domains. Link pages together with descriptive links and put a site map link on every page.
The more pages that you have in a website with good content on them, the more likely that one (or more) of those pages will appear in a web search and hook a surfer.

Keywords:
Put keywords in Bold or Italic. Use keywords as the name of named anchors on your site and use links on the page to jump to these named anchors. Try to figure ways to call attention to your keywords, like putting them in headings and links. Put keywords in the title of your page. Make sure that the name of your page is not something like page2.htm. It should include keywords like Creating_Traffic.htm. Put similar pages in directories and the name of the directory should be keywords, not an abbreviation, but a verbose set of keywords.
Use the word Free somewhere in your site. Put it in an H1 tag, but use a css style to bring it back to ordinary size text. Everyone is searching for free stuff so they if they search for Free Quality Traffic they will be more likely to find you. If you are bold, use the word Porn in conjunction with free. Free Porn is the still, by far, the highest rated search phrase, even if the traffic you get from these freebie hunting voyeurs is not that good.

Don’ts:
Don’t use banner exchanges, link farms, automated link exchanges, free-for-all links, pay-for-links or anyone who guarantees a certain number of clicks. You need natural quality links, not links from flashy animated gifs or sites that force surfers to click in return for something.

Measure the results:
Register with MyBlogLog.com and Google Analytics and watch your website traffic. The free version of MyBlogLog gives you great information about who is surfing your site, where they came from, what pages they look at, and where they go when they leave.
Unlike raw web log analysis, MyBlogLog and Google Analytics don't show you spider traffic or hits on graphics, css and other files. It shows you real traffic by people who have JavaScript and are looking at your website. Yahoo bought MyBlogLog and they have a lot of community features and I actually get some traffic back from their website.

None of these mechanical methods for building inbound links will replace a good site with useful information. Surfers are looking for a payoff. They won’t come to your site unless you promise them something. You have to pay the surfer when he gets to your site or he will never come back. You can promise the world, but if there is no payoff, the surfer click the back button before the page has finished rendering. Natural links are gold, search engine links are your bread and butter, but a link from a surfer who has bookmarked your site is money in the bank.