bpowerd is a daemon and makes proper use of the system log for error checking. It uses init's powerstatus calls to do it's dirty work, instead of calling shutdown itself. bpowerd is easy to compile and configure, using GNU's autoconf and providing explicit instructions for testing and installation. bpowerd was created using specs provided from the manufacturer, as opposed to reverse-engineering.
Pulsard allows you to monitor an MGE Pulsar UPS to initiate a clean shutdown in case of a power outage. It also monitors the quality of the power line. It has only been tested on Linux with the Pulsar ES8+ and the ESV8+. It uses libgpio (from the gphoto project) to communicate with the UPS, making it easy to extend it to other communication channels than RS-232.
printerpowerd is a little Python script designed for users of older printers who want to save power when not using their printer, without manually turning it on and off. It runs, checking the printer queue directory every five seconds, turns it on when it sees a job, and turns it off after a configurable amount of idle time.
inpowerd is an inetd server that receives power event notifications over the network and notifies sysvinit about these power events. It is useful when more than one machine is connected to the same UPS but only one of them communicates with the UPS directly. The rpwrstat utility, which is distributed with inpowerd, can be used to notify inpowerd about power events. The rpwrstat utility is easy to port and currently known to work on Linux/Unix and NetWare. The rpwrstat distribution contains a compiled NetWare Loadable Module which is tested on IntraNetWare 4.11. This makes it possible to connect machines running NetWare and Linux to the same UPS.