Today's discovery: SimplifyMedia, a very handy media-sharing service. It lets friends listen to your iTunes music library from their computers, no matter which network you or they are on. It's even useful if you have no friends: if you use more than one computer and want to be able to access your music on all of them, SimplifyMedia does it.
At the moment, the service works only with iTunes, and most iTunes users probably know that iTunes already allows streaming between computers. The hitch is that iTunes restricts sharing to a local network, so music can be shared in a building, but not across the world. You can hack around this with a virtual network product like Hamachi, but that's beyond the technical reach of most people. Orb also lets you share your media libraries, but I've found it buggy, and the browser-based interface is slow.
SimplifyMedia makes things automatic if you want to share across the Internet. You can invite up to 30 other people into your library, and see their tracks as well. As I said, what I find most useful about the product is that it gives me easy access to my home desktop's iTunes library from my work laptop, no matter where it may be. I keep a large music and podcast library on my desktop at home, and this tool makes it easy for me to access it from iTunes on my laptop, even when I'm at work or on another network elsewhere. It's like a Slingbox for music.
The service keeps things legal by allowing only streaming, not copying, and only to a small group. Also, only you can listen to your own iTunes-purchased, DRM-protected tunes. The Simplify team is working to loosen up that restriction.
My big criticism has to do with access control. It's binary--when you let people see and play your library, they have complete access to all your nonprotected music, just as you do. I'd like a better way to restrict visibility for people I've given access to, while maintaining full access for myself. Also, I found a technical conflict between the beta software and my home's media storage drive--I could only have one working at a time. There are also reports of VPN incompatibilities, but none popped up in my tests.
This application is a natural for the Facebook community. SimplifyMedia co-founder Paul Joyce says the team is already working on it.
See also TUAW's interesting history lesson on iTunes sharing.