Although Apache is the default choice of web server for Rails, it is by now means tied to it. Any web server that’s capable of doing a wee bit of rewriting in front and handling FastCGI applications can run Rails. Lighttpd is just one such web server.

If you’re interested in trying that out, TJ Vanderpoel has written an extensive tutorial on how to get Rails running with Lighttpd using FastCGI on Debian.