Jack Arnott on the Guardian Food Blog gets slightly wound up about tipping. I must admit that, like him, I'm never entirely sure of the protocol. One good thing about Austria is that when they tell you how much your meal is, €15,60 or somesuch, you can just round up and add a bit and say "17" and it's taken care of. They get the change that you really didn't want all that much.
The article also links to an list, in PDF format, of the various International differences to the "10%" rule of thumb. Oddly fascinating.