Our remote wireless site keep being unplugged or having the circuit trip from some combination of cleaning devices. I took a spare UPS and asked if we could get a $200 SNMP card for it so we would know when the power was off. Boss asked me if we could do it for less.
My solution: $70 IP Power 9200 delux. The IP Delux has 4 voltage input sensors, 4 current sensors and 8 web controlled switches. There is a 5v wall wart plugged into the switched part of the UPS running to a input. When the power goes out the ups kicks in running the POE and the wall wart turns off pin 1 on the IP Delux which sends me an email.
The added bonus is that the POE is now switched so if a AP on one wireless segment locks up I can go in one of the others and power cycle the POE remotely. IP Delux even hosts WAP so I could do it from the cheapest of cell phone web browsers.