Tectonic, I was an RoR freelancer for 2 years. Here are sites where I've found jobs:

http://jobs.rubynow.com http://jobs.37signals.com http://bostonrb.org/jobs

If you also just google "rails jobs" you'll find the other useful rails job sites out there.

The best way to find work, however, is to build your network. One of the best clients I had was referred to me by a fellow I happened to have lunch with when I was in NYC for a couple weeks. Another of my best clients was referred to me by a friend. Where are you located, btw?

Another way to find work is to find other web development companies and just email them asking if they need help. I've found work this way as well, and have had more success contacting local companies.

edit: One thing that helped a lot was I developed a rails tool (Palmist, http://www.flyingmachinestudios.com/projects/) , then I gave a presentation on it at the Boston ruby group. Since then, many interviewers have perked up when I mentioned it because they had either seen it or used it.

Hope this helps!