Building a super UPS
 

My application, however, demands a bit more. I have a fully kitted-out office at home with a workstation that runs two PCs, a 4-in-1 digital scanner/printer, an inkjet printer, a DSL broadband router, a wireless network router, and two sets of speakers. There are also a fax machine, and a mobile handset that is useless when its base goes dead.

http://icrontic.com/articles/super_ups