Okay, so I was thinking the format could be; someone posts an artist they like, in order for other users to reply with recommendations of similar music. Thises (to suggestions) would help determine good suggestions. A few pointers:
Keeping replies, other than recommendations, to a minimum would help declutter. Longer posts are fine however (to a point of course)
And yes, last.fm does this...but it shouldnt be a patch on the wisdom of this community. Nonetheless, dont choose something too obvious (radiohead fans might like thom.yorke etc).
I'll get the ball rolling...