I have been frequently referred to things posted on the WFMU Blog:
http://blog.wfmu.org/freeform/I'm not sure that this place has been brought up as a location for eclectic sound MP3's but they definitely have those! Right now I'm listening to some Fuzzy Country Guitar music and before that I listened to comedy by the late Roger Price (funny stuff) who I don't think I'd ever heard before. Good place to go for different things.
Later: Warning, this website above loads "very" slowly under Firefox on my old G4 (lots of spinning ball) but seems a little bit more speedy using Safari!
Even Later: The Roger Price piece I really liked was the one about the true roots of jazz in the maple sugar workers in Vermont!