An exciting development for art lovers is the emergence of web-based artists communities and art groups that have sprung up in the last few years. Ranging from simple gallery-hosting services to extremely interactive sites that allow commentary, ratings, reviews, chat, contests, and facilitate communication between artists. The speed with which artists can interact and see each other's work allows rapid stylistic cross-pollination and collaboration.

Deviantart.com an extremely popular art community, also has a "mosaics" feature where artists collaborate on new pieces using a grid system. Someone decides on a theme, and starts handing out grid squares to volunteer artists. Some of the results can be seen here: Mosaic Section of Deviant Art

Deviantart's popularity probably stems from the instantaneous feedback you get when you upload an image. Often, a new item will start collecting comments from the huge viewership immediately. Interacting with your "fans" is easy, and you can see what other artists they like, and what they have uploaded or written. Quality varies, but the energy of the site is addicting. It's just way too much fun.

Raster is less of a free-for-all. New members are recruited by the group, and the overall quality is very high.

Abnormis displays art by their featured artists. Anyone can submit artwork. Portfolios are reviewed by the staff once a month, and 5 new featured artists are chosen.

The competitive side of art is brought out in the "Photoshop Tennis" matches hosted by Coudal.com I particularly like this match, featuring some of the most beautifully rendered insults I have ever seen: Schroeder/Grosh Match