T.I.P.S as in "To Insure Prompt Service" is a common misconception. I can't remember where I read it but it actually doesn't stand for anything, if I remember correctly. I always used to used to use "To Insure Prompt Service" when discussing tips though lol.

As for restaurants, yes I tip when a tip is deserved, which is almost always. If the drink stays full, if the food comes before it is cold, if the person is nice, and if a server has made an effort, yes I reward the extra effort. Having been a server, I know how challenging the job is and I know exactly where the "extra effort" comes into play. I have stiffed servers in the past. I have also tipped servers nearly 50% of my check value too. It all depends on the "extra effort." I do have to agree with Mr. Pink though, I do not usually feel any societal pressure to tip. If it is earned, I feel a MORAL pressure to reward extra effort.

As for bartenders, if the drinks need to be made and are good and quick, I tip greatly. If the drinks come from a bottle / can (beer), then I usually do not. If I get a large number of tap-filled beers, as long as the head stays minimal, I'll tip but not nearly as well as if I were getting quality mixed drinks or something like that. If it is hugely crowded and the bartender is busy as all heck and he passes over two good looking ladies and three obviously rich people to get me my bottle / can beverage, absolutely!!

I do not tip hotel house keeping. The only time I would is if I was just getting there and they just started cleaning the room and they FLEW through the cleanup. That is the only opportunity I can imagine where I would feel a duty to tip the maid staff.