I listen at work mostly via J. River Media Center accessing my own collection via Library Server function over WAN, but do use Last.FM to track my playback and listen on my iPhone in the car (Simplfy is another killer app I use to stream music from home to iPhone).

I just subscribed to MOG for 6 months; it looks pretty interesting. A more advanced direct searchable/playback version of Last. FM/Pandora.

Should be good for checking out new artists etc.