It's a surprisingly lucrative thing to do. Admittedly I've been building my Amazon profile for years, with uploading book reviews there, but I'm getting multiple emails a day from various sellers who see that I'm decently high in the rankings there and want to exchange a free product for a review. I've been offered everything from new headphones to silk pillowcases. And I hadn't thought about doing it with freebies offered to everyone by companies until fairly recently, but there's no reason why I shouldn't, and I'm sure that's why half of them offer those "email us today and we'll send you a free sample of [whatever]" deals anyway.