This might be of interest to you too: http://www.cohprog.com/mod_bandwidth.html, though I don’t know if it’s still active, or if it works across apache v 1.x and 2.x.

The good side of the iptables approach is that it can be used to limit concurrent connections to any network based service

Good luck,

I have been trying to find a way to prevent Apache from spawning too many child processes whenever some bad robot or hacker throws a bunch of concurrent requests at our website.

This may just do the trick…