Free Linux versions of APC UPS management software. At least 4 distributions supported: Caldera, Red Hat, SuSE, Turbolinux.

UPS power management under Linux for APCC Products, including models BackUPS, BackUPS Pro, SmartUPS V/S, SmartUPS(NET/RM).

Program to monitor Best Power Patriot and Patriot Plus UPSs under Linux. Uses init to inform system of power outage, is able to detect power fail and low battery conditions, and to kill inverter on shutdown.

A free Gnome client for the Network UPS Tools (nut-0.42.1) package released under the GNU GPL.

An inetd server program useful when more than one machine is connected to the same UPS, but only one of them communicates with the UPS directly. freshmeat.net [Open Source, GPL]

Support page of project to monitor all UPS types with enough interest. UPS drivers in package convert status data from native hardware format to common scheme, let you manage many UPSs from varied makers with small set of programs.

A daemon which can monitor a UPS and safely shutdown the computer when the power goes out.

Using UPS with Linux: case history, how-to, several links.