"Wotartist is unique in being an artist directory run voluntarily by artists themselves. It is a non-commercial site, with the sole aim to promote some of the best artists currently exhibiting on the internet. Designed with ease of use foremost as a consideration, we hope that the buying public, publishers, art students and art agents will all find wotartist a useful tool. Please contact directly with individual artists if you are interested in their work and send selective artists e-cards - which can be used for all occasions. New artists are actively sought out and added to this site daily, so please visit frequently to discover new and exciting art work."
There are a lot of excellent visual artists represented on this site, Wotartist, including several collage artists. This site is one of the 50 internet sites for 2007, according to Time.
I am happy to be a participant of Wotartist, and suggest that you take a look at some of the artists represented there.