I’ve been using a cool service online called MediaMaster — it lets you upload your music collection to their site and listen to it anywhere (using either their online player or streaming it to your own desktop music application). Best of all it’s free!
I find the interface for organizing the music online really clunky — everything is Flash-based, so it goes really slowly. But now that I have all of my music on my “Radio” playlist, I don’t have to mess with that. I just pull up the stream in Windows Media Player at work and listen to my heart’s content.
I don’t usually brag about the coolest new thing that I’m using, but a couple of people at work have asked me about it and were impressed with everything that I told them. By the way, you can also listen to my music stream if you like anything specific I’ve got on my playlist. Here’s the address you plug into your music player: http://n91.mediamaster.com/myradio/cgibby.pls