http://www.tipthepizzaguy.com/
believe me, you wanna tip the pizza guy. UPS and Mail delivery don't use their own vehicles, get paid extremely well, and don't generally have to worry about being robbed for cash.
Pizza guy even has to pay for his own gas...cmon, in this time of $2/gallon gas, he's probably losing at least 2 dollars ever 20-25 miles...
and don't forget, if you're a frequent guest at a restaurant or caller to a pizza place, they remember...beeeelieve me, they remember...So, while you may tip generally well for good service and nothing for bad, remember that servers talk and if you have a bad tip reputation, your service will probably decline as well. Servers generally spend more time on tables they don't know or know will tip well instead of wasting extra time with tables who are known for being low/poor tippers.