Apache::Quota – This module provides flexible transfer quotas for all or part of a site. Additionally, limiting may be for the site as a whole, on a per-client IP basis, or based on some other criterion you choose.
Net::Shaper – Net::Shaper can be used to implement a point-to-point TCP tunnel that limits bandwidth.
Apaches::Traffic – This module tracks the total number of hits and bytes transferred per day by the Apache web server, on a per-user basis. This allows for real-time statistics without having to parse the log files.