Linux Bandwidth Arbitrator allows beginning-to-advanced network administrators to control bandwidth. It is designed to be completely turn-key in its default configuration. You just plug it into your network trunk, and it self configures and immediately starts slowing "bandwidth hogs". It can be configured to target specific applications such as Kazaa, IMAP, and POP. It is compatible with the 2.4.25 kernel, ebtables, and brouter (bridging router). It also comes with denial of service protection.
APcrond is a very lightweight Perl script originally developed to run on CDROM-based Linux systems that may not have access to writable directories. It is also nice to use as a personal application scheduler, as multiple simultaneous copies can be run. It follows most of the standard Unix cron conventions.