Haha! I have a nice big APC UPS for each main stand. It really is comforting to know you don't have to worry too much if the power konks out for a bit.
If you're very protective of your tanks, or just in a bad area as far as power/electrical storms/ice goes, I'd highly suggest it.
You can get cheap-o UPS's from about $30 and up. The higher the capacity, the higher the cost. The more capacity you can fit into your budget, the longer you can go without power. To squeeze every last drop of juice from the low-tech batteries UPS's use, I only put "tank-critical" devices on them. (filters, pumps, airpumps sometimes) The fish and plants can live a while without lights, not so much with some of the other powered stuff.
If you're a super nerd like me (or just a DIY freak), you can snatch a used UPS with a bad batt (read: uber cheap) and rig it to run on car batteries or any other high capacity ~12vdc battery. You can get some VERY impressive run-times with substantial loads on a decent car battery's charge.