for the narrow focus of the folk/acoustic world, what I like to to see is a web site..(whether by the artist or the promoter/manager) with some sample cuts (even partial cuts...one verse)...in MP3- and a list of songs and general description of 'style'. I have seen this done various ways, and will see if I can find some examples.

Then such sites could be mentioned here, in rec.music.folk...etc....(I don't want to be inundated with sales pitches, but a permathread with lists of stuff available by members would be quite uesful...we are 'close' to that now with 'who's performing where)

This would not make you rich, but exposure has to start somewhere.