Everywhere, that's where.
Starting up an online gallery (which I've kind of hinted at) means that the first place to look is, well, online.
Here are just a few places I've been going to discover a mountain of great new artists:
Flickr - not just the home for photography, it's full of amazing artists that are using it to promote their work. In particular I'm finding great artists through flickr groups.
Myspace - Two months ago I'd hardly ever been on myspace. Now, I'm in love with it. Even though people are flocking to Facebook by the thousands, Myspace is still the place for up and coming artists to put together a portfolio of their work.
Blogs and Online Mags- Of course, I'm finding heaps of inspiration though the blogs I've been reading. Creepmachine, Lost at E Minor, Little Chimp, and Juxtapoz are just few of the many feeds I'm hooked on.
Deviant Art - I mentioned this site before, but didn't realise just how huge it is. Plenty of great artists with their work on show here.
The next step (other than to build a website) is to get enough artists involved in the project. That's gonna be the hard part.