anything like di.fm, nearly no commercials? the quality is absymal though so if theres other good techno/trance stuff that would be nice. rock is good as well.
pandora.com is sweet you give it a band, and then it creates a station for you with songs/bands that are similar to that style, no commercials
I used to be all about Pandora, until I discovered: http://www.slacker.com Any music you want, free with no commercials.
For Tejano/Conjunto/Regional/Mexican or Top 40 Oldies, www.bnetradio.net. A friend of mine is a DJ for the TEJANO station. I highly recommend it... plenty of oldies. I second this one. It is very good. My wife listens to this even at home and it annoys the sh*t out of me, so it must be good.