Use Leopard’s Time Machine Over the Network
Via Lifehacker: Mac OS X 10.5 Leopard came with a new, easy-to-use back-up program called Time Machine. For people with an extra external hard drive, this was a godsend. If you also happened to have an AFP share over the network, you could backup to one of those as well. But if you’re like many of us who have completely abandoned AppleTalk, Time Machine was pretty much useless until now.
iTimeMachine is a program from Xiotios Software that lets you use network shared drives in Leopard’s Time machine. Simply mount the network disk (don’t just browse it; actually mount it using the “Connect to Server” dialog in the finder), and then it should show up in Time Machine as a backup location.