I gave up buying singles a long time ago, it seemed pointless. £4 on a CD with, maybe, four tracks on it, or £9.99 on a CD with a full album? There wasn't really much of a contest. Equally though, I was loath to payout for an entire album of an artist when I only really wanted one of their songs. With the growth in downloadable music I have started to buy single songs again. One of the reasons for my resurgence in buying individual tracks is movie trailer music.
As I've mentioned on my film blog, the music on most trailers is not going to be in the final film because the track listings and score is usually one of the last things to be finished, but they often have some cracking tunes because they really want to 'sell' it to the audience. I've found a few great tracks of late.
Most recently I bought Kasabian by, er, Kasabian because I caught their track Club Foot on the Serenity trailer and thought it rocked. Obviously I had no idea what it was, but I've found the best way to get the name of the tracks on trailers is to check out the comments on the film over at IMDB. IMDB is the movie bible (you have to sign up to see the comments now, that's new, it's free though). Anyway, everytime I've looked for what the tracks on various trailers were, they've always had the answer. Using this technique I've managed to grab The Slam by Tobymac off of the Transporter 2 trailer, Learning to Fly by Tom Petty and the Heartbreakers from the Elizabethtown trailer, Rock Star by N.E.R.D from the Taxi trailer and going further back, bought Frou Frou's album after hearing Let Go on the Garden State trailer. All by using IMDB to track them down.