Network UPS Tools (also known as NUT) is an extremely powerful and versatile client/server based approach to UPS monitoring. Products from a wide range of vendors (APC, Belkin, Best Power, MGE, Tripp-Lite, etc.) are supported. A shared UPS can be monitored by one host, notifcations being sent to the other hosts via authenticated TCP connections. A Web interface is available, as is a Windows client.
Just to confirm, the NUT website is indeed www.networkupstools.org, and the mailing list page on Alioth should work to get in touch with the developers. If anything appears to be down in the future, and you can't contact us via the mailing lists, you could also try to reach us via the freshmeat "Report problem" link above.