mod_choke is a module for Apache that limits usage by greedy clients.
It's two main functions are to limit the number of concurrent
connections per IP, and to limit the rate at which apache sends data
to the client. It includes detection of users behind proxy servers
(using the X-Referred-By header). It includes limiting the speed at
which files are sent to a configurable rate, with the option of
allowing a burst at full speed for the first chunk of a file.