15-20% for food service. One quip about this: I absolutely despise receipts on credit card bills that have a "tip" line when the restaurant does NOT have a wait staff NOR a delivery staff. There is a local sandwich shop here (think subway) that has a f-ing tip line on the receipt that suckers me everytime.
$1 per drink at a bar. Which brings me to another story. For my brother's bachelor party, we went out in downtown Denver. Right off the bat, I ordered 8 shots of Patron for $60. This was at like 6 PM, so we were literally the only people there at that time in a huge bar (it was the Tavern in Denver if anyone is familiar). I gave the bartender girl a $10 tip, she scowls at me and says "That's it? The tab was $60, that's not even 20%!".... I've never yanked a $10 bill off the table so fast in my life. THEN my brother gives me an extra $5 to go back to her to apologize and give her $15. I was blown away.
$5 for a haircut.
Cabbies are a different beast. I've only taken about 25 cab rides in my life though. I learned quickly that I should know the routes to where I am going before I get into a cab, or else they drive around for 45 min and run up the tab. Now, I pretend I'm a tourist anyway. If they bring me straight to the destination like a good boy, generally I throw $10 their way. If they drive around in circles for 45 min, I stiff 'em, and tell them I knew where I was going the whole time but nice try.