There are not too many widely used web frameworks outside of rails in Ruby. There is camping which is a microframework. is there a reason why you dont want to use one based on rails? [ June 19, 2007: Message edited by: Prabhakar Chaganti ]
FWIW, my book has an example of using Ruby and RMagick to generate static HTML pages; should be feasible to port it over.
There are non-Rails approaches to frameworks, of course - camping is a good example, and so is Og+Nitro. I'd like to see more lightweight Ruby frameworks - not that they will replace Rails, but I'd like to see more single-file, drop-into-your-public-html-directory-and-it-runs solutions. (Of course, that's something you can do with PHP out of the box on most distributions.)