Building back links is something I really want to learn more about. I do a lot of blog commenting, do reviews on my blog and I do use links in my forum signatures BUT I think it's best to add more to a signature than just a link with a keyword phrase. Forums are communities where we get to know other members and I'm more likely to click on a forum signature IF they have more meat to them or at least a name.
I do know that I should be writing and distributing articles to directories.
Great topic to discuss.