Autonice is a simple Perl script intended for multi-user systems.
The script regularly surveys any CPU-consuming processes on the system, and if any process has been using more than a given amount of CPU-time, the process is reniced. A mail is sent to the user. Autonice is known to run on Red Hat 4.1 and 5.x systems, both Intel and Alpha.
As the script is quite simple, it should run on any system using a Crontab file, the /proc file system and an installed version of Perl.