There are several that I know of:
ARTCRIT
PAINT-L (mostly for painters)
ARTLIST
EAS-URI (Univ. of Rhode Island's Experimental Art Society--a quiet one)
ART-ENVIRONS (mostly about art in the environment and outsider art)
WAL (Women's Artist List)
I used to get ArtCrit but it got too in-crowd-y for me. Paint-L is good for
technical tips and the odd philosophical discussion. ArtList has a lot of
flamers for a listserv but is OK. EAS-URI is quiet and is run by a
musician, but they discuss art as well. Art-Environs is fun but frequently
wanders off-topic. WAL is also good but very militantly feminist, which
some people may not like.
I also check rec.arts.fine occasionally and there can be some good talk on
there, if you can get past the flame wars.
Instructions for subscribing to all can be found at www.tile.net
Have fun!
Julia Moore
Indianapolis Art Center