I'll use Napster to DL the one good song by many of today's "one hit wonders" or find some rare out-of-print stuff. Mostly, I use it as a huge listening station - If I hear about some band or hear a cool tune, I'll get some more to see if it's worth picking up.
Latest example was the Matthew Good Band. I loved the track "Load Me Up" (saw the video on MuchMusic and got the track on a CMJ comp, so it's legal), so I grabbed a stack more and really didn't like it! It sounded like a cross beween Tragically Hip, Matchbox 20 and Counting Crows, three of my least fave acts. His CD was on sale that week at Beast Buy for $8 and I would've bought it in a heartbeat, but instead saved the money, deleted the tracks and moved on.
OTOH, I've bought Outkast, PJ Harvey, Eminem, Fiona Apple and many more after checking out enough tracks to ensure that I wasn't gonna get clocked with a dud. I usually delete the MP3s of my HD to free up room too.
Records are overpriced and the labels are greedy and they don't pay their artists much, but unfortunately, too many Ferengi believe that they're entitled to free everything for some reason. This is why the industry doesn't want to come to terms with the new taste for instant afforable music. Too bad.