CGSociety is a paid subscription site, about $40 a year. But it gets your work seen by a hell of a lot of people. And they also have some special offers as part of the package that might be of interest. I’ve had my crap up there for the last few years and have made a lot of cool contacts through it.
I’d also recommend you post a copy of your portfolio to http://www.deviantart.com/
Also hugely popular.