Can't help with the rock/hip hop, but for electronica (and its ilk) I would recommend: soma.fm (or, apparently, somafm.com, now.) (For example, the "cliqhop/id

Can't help with the rock/hip hop, but for electronica (and its ilk) I would recommend: soma.fm (or, apparently, somafm.com, now.) (For example, the "cliqhop/idm" shoutcast stream is what I use when I need non-distracting music in the background, for working.)