MP3 Links Generate Album Sales
I'd love to see someone do a formal study of this (not that the RIAA would fund it, or anything), but it's always been my personal belief that direct links to MP3's in places like blogs and bulletin boards ultimately lead to sales. The paralyzing fear that folks have around sampling prevents us from enjoying the big picture -- sampling creates audience.
So, in that spirit, Fred Wilson reports some anecdotal evidence that the links from his blog generated about $4,000 in Amazon affiliate sales so far. And that's just what he can track.