Not to long ago I found out about Spotify, the online music steaming service. It's ad-driven, or you can pay £10 a month to have it ad-free, and you can listen to what you want.
The thing is, that so far, I haven't been able to not find something on Spotify. I know they don't have everything, but I have never thought "Oooh, I should listen to that on Spotify" and not had it playing within 20 seconds.
To the delight of copyfighters everywhere, this source of endless free music has, of course, meant that I buy more music. Let me explain with an example:
Recently I heard a song on the radio I really liked. Stupid DJ didn't name it, but I remembered enough of the lyrics for Google to be able to find it. "It Happens" from "Love on the Inside" by Sugarland, if you care.
Of course, it's on Spotify, so I could spend a week listening to the whole album as much as I liked, on my Mac at home or my PC at work (roll on the iPhone version!).
I eventually decided that I like it a lot: a few clicks on iTunes (after checking if it was cheaper on Amazon, of course) and it was bought.