Hey,
I've written an ICP responder, that would help a lot in squid-apache web server cluster balancing. It does delay requests to frontend caches at high loads, sends immediate responses at idle cpu capacity and might be remotely turned on or off at emergencies. Right now due to Linux kernel scheduler granularity it works at 0/10/20/..ms steps, therefore it does not achieve my design goals (milisecond-level delays), but still, it works with superior functionality, and does not need hacked squids installed on apaches.
Source location CVS:extensions/icpagent wm:~midom/extensions/icpagent
Docs: http://wp.wikidev.net/ICP_agent
Cheers, Domas