If you want to stream any kind of music, try
sky.fm 
Personally, I like instrumental jazz. A few of my favorites are the Rippingtons, Sypro Gyra, and Lee Ritenour. Some would call this "smooth jazz", but I find the styles that the Rippingtons play change through their playlist. My favorite album is their "Live in L.A." concert disk. There are quite a few videos of their performance in L.A. on youtube.
