FastCGI Ruby dispatcher
This seems to be a nice script, to be honest I haven’t had a close read through the source, but it looks reasonable enough that I’m using it.
To set this up on FreeBSD you’ll also need to pkg_add -r ruby18-mmap. The rest of his instructions work fine, although on FreeBSD one should install ruby-cgi to /usr/local/bin rather than /usr/bin.
Enjoy.