The BBC has a good rundown of how much you are expected to tip for various services across the world. Americans who are accustomed to leaving 15% at restaurants often leave too much when tip may be included in the final price.
You’ll never have to tip anywhere in China. It’s the one consolation from the fact that foreigners are charged more as a matter of government policy.
Canadian waiters will often bluntly tell you they don’t work for nothing (read: Montreal) and remind you to tip generously for their service. (A good range is 15-25%). In general, tipping is catching on in many parts of the third world but still make sure check if it’s a faux pas before dropping some change.
[photo by: alberth2]