I've blogged about BzzAgent before and I'll do it again. All you have to do is sign up to participate in their campaigns. You can sign up here. The only requirement is that they want your feedback on the product. You try it, decide what you think about it and log back into BzzAgent and let them know.
I can't wait to try it out this week. I'll let you know what I think. If you're interested in other websites that offer similar benefits, check the left side of my blog under Favorite Sites to Visit and look for the sites that say product trials. Who doesn't love a freebie in the mail????