Create a fan page on Facebook, get 25 followers and they'll give you your own facebook url
I would mention Comicspace (which I've never used), but some people are complaining about that one these days. If you don't mind banners above and below your site, you can create one for free at www.tripod.com
It always looks more professional if you have your own domain name, but that costs money. Once you're off and running, so to speak, it's worth the investment.