The Southern Nevada Rock Art Association meets on the fourth Monday of every month, starting at 6:30 p.m., in the REI store in Boca Park. Admission is free and anyone interested in rock art is invited to attend. There's usually a program on rock art and/or archeology. most often local or regional.
The group holds outings for members every month and works to protect rock art and archeological sites in Nevada. Their website has links to a host of great rock art websites.