Youtube, social bookmarking, directory submission, guest blogging and forum posts. Lots of good tips on this thread, good luck!
I strongly believe that guest blogging on high PR blogs is the new way to go. Really sucks to do all this by hand but it will much more rewarding. If you don't want to write always check the warrior forum and DP for writing services and hire a write to write you an article on a needed basis. Really you kind of want to stay away from article directories and the trouble it brings especially your business model is depending on free traffic google, bing and yahoo. You buy your traffic it would say it doesn't really matter unless you decide to sell it one day.