Directories, Blog Comments, Paid links in Sidebars of a few popular blogs .. others just purely type in my adress
That pretty much covers it.. To get ideas on specifics (directories, blogs, etc.) it is helpful to see where your competitors are getting their traffic from. You can check the links to other sites through google ( link:<site address> ) or get this information through Alexa.
Best traffic (most reliable) is Search Engine Marketing or pay-per-click - in most cases Google is the best followed by MSN and Yahoo. Search engine organic traffic is good if you can get it. Blog ads are good but tend to wear off with time due to repeat visitors to the blog.
I use a little known secret only to those from years ago....lol j/k I get good traffic from paid banner advertising on relative sites, obvioulsy on non competitive sites, just how we all used to do it but I dont pay impressions just a set monthly fee, probably the best targetted traffic I get everyday and there are still good deals to be done there.
This is rare: what very good quality traffic is to get your site written about in a popular news-type site... (such big names like ABC, CNN, etc). Rare though!
I spend some time on it several times a week. There are tools that can help like the tools in Adwords Admin.