I'm extremely interested in modding m0n0wall to incorporate a cacheing http
proxy server.
You'd still boot from a CD/CF, store settings on a floppy, but you'd also
have a single high-speed disk to act as a cache store.

Has this already been done? Would I be re-inventing the wheel if I added
support to m0n0wall?

I'd probably use 'oops-cache', or apache's caching proxy, rather than a
bloated squid.
Or, I could use a php-powered proxy, as php is already installed on m0n0...

Any ideas?

N.