Just wanna throw this out there.

www.entrecard.com

This site is quite similar to Bloggers.com. Except that your job is to visit new blogs, drop your card (like a business card) and comment a couple of posts. Everyone there does the same thing.

My personal opinion: While it does provide a great boost in traffic stats, I just don't see them converting to buyers or let alone, click on my ads. I used to be on entrecard, now I just have an account there just to read new blogs.

Go ahead and try it out yourself.