Please Keep Winamp Alive!
It really does whip the llama's ass.
I have been using Winamp since the late 90s, and have found nothing to compare. I have found some useful MP3 players; but none with the feature set, library flexibility, and concision (Thanks for that word, Jack 23.) of Winamp. And absolutely nothing that can compete with Winamp's visualizations. I used to set up a playlist of soothing music, with full-screen visualization, timed to play something suitably rousing when it's time to wake up, dream machine, and alarm clock (and soft light for getting up in the middle of the night). Although there is always the risk of getting sucked in and just watching the visualizations for ...way too long.
I also love the fact that a playlist can be as long as it wants to be, or WinAmp can handle a library. I usually use the bloody-near infinite playlist, (7-8 weeks continuous play, last I checked) set on shuffle. I also like how Winamp handles randomized playback, with many options, depending on how you like your random.