You can stream music, pictures, and videos to multiple devices at once.
Go here and download Orb. After you download it all you have to do is setup a Username and password. Then you'll be able to stream music and videos from your PC to 360, PS3, Wii and other things.

I have got audio to work for my PSP, Wii, and 360 and they work very well. I haven't tried video but I assume they would work, except maybe not for the PSP. UPDATE: Video doesn't work on PSP but it is excellent for the Wii if you have the Internet Channel, it keeps excellent quality, maybe even the same quality as if it wasn't even being streamed! The only downside is it takes quite a bit of the CPU.

Odd side note: I can't activate my laptops camera with anything on my PC but with this program I was able to activate it via 360 and the PC streamed the camera onto the 360.

System Requirements: here
Getting Orb to work with Wii: Link
Getting Orb to work with 360: Link
Getting Orb to work with PS3: Link