There are 6 forms of traffic that i will talk about read thoroughly and try it...
1. Startup page traffic.
This is normally called your browsers homepage, just like Google, MSN, Yahoo, search usually the first page you see when you load your browser. Now theres many ways to do this, you can set some scripts or buttons on your page, or try to force it with many tricks to make the end-user set your page as your homepage.
The most profitable method for this is to throw up your own search engine with adsense ads or XML ppc companies search scripts. All are profitable but it would only work if it was good, and you dont want to throw just a crappy page up as you will annoy newbies who dont know how to change it to whatever they like. So a search engine is good because if they cant change it your going to get a lot of searches made, meaning money for a long time.
2. Typein Traffic.
As everyone here knows typein traffic can be very great at converting, say for example a friend of yours told you to visit "U TUBE DOT COM" if you did not know it from the start you could take this in a numerous amount of ways like UTUBE.com, they are really sought after domains that only usually consist of DOTCOMS because not many people will typein a .NET, anyways these domains if you can grab them are great earners. The best method of grabbing one of these is looking for beta release sites, like http://www.inviteshare.com/ this will tell you invite only sites, that are not yet public, these can be amazingly fast ways to grab upcoming potentially great traffic sites. And if you snap up typos fast could make a great earner, or a domain sale.
Bookmark traffic depending on what kind of site always leads the user back to you. These are mostly community sites or blogs, well , all sites really get bookmarks but the popular ones are usually member sites, like blackhatworld for instance. The earning potential here is great, and the traffic is recurring for a very long time, but i wouldnt recommend forcing a bookmark using scripting as that will piss the users off.
4. Linked Traffic.
This is where most of your traffic should come from, Search engines, links from blogs, directories and whatever you can think of that has link potential like blackhatworld here. The traffic is usually targeted because your anchor text is usually relevent to what the user wants to see.
5. Popups and redirects.
Popups and things can be sent from other sites, exchanges, and popups from your other network of sites. You can easily get a lot of popup exchanges to your site(s) but the traffic is poor, usually only good for the likes of PAY PER IMPRESSION.
A lot of software can have built in browsers, or banners, the likes of MSN messenger always usually runs an ad at the bottom of the client. This converts into traffic by clicks, and mega targeted, you can also throw traffic in your own browser, for example ebooks, and other things like that, i put ebooks here under software because sometimes ebooks can be binded into software, but its all the same, ebook traffic can be very converting , and say you write about something and spread it through torrents, p2p and other things on the subject you want to convert it can get viral.
Viral traffic is another using the buzz to spread the word, for example the likes of youtube videos, you can throw in a lot of funny videos and watermark your urls on the video.
Another idea would be to upload the latest songs in the music charts to youtube or other type sites and throw in a ringtone affiliate url in the description.