Nginx proxying to multiple RoR apps

So I took the plunge and I purchased a basic Linode box to give myself a place to experiment with building RoR apps.

So far I've found success in setting up Ubuntu 8.04 running Nginx that proxys to a single mongrel server.

My problem is this: now that I have one project up and running, can I can setup a second RoR app/domain name and have Nginx proxy requests to that one too. (without disturbing my current app)

I haven't been able to find an example of an Nginx conf file that does this and if I try to load up another Mongrel (ruby script/server -d) it throws a "Port such and such in use error".

At this point I'm not sure if I'm asking the right question or where to go for documentation on this kind of setup so if I could get help asking the right question that would be a good start.

Thanks in advanced,

-Matt