I consider tipping to be an indicator of what kind of person you are. I don't really care what other people think of what I mean when I say that. I tip well and reap the benefits.
(warning slightly long-- but I think I have a good basis for tipping)
I usually tip around 15% at all restaurants, whether it is a cafe or an upscale dining arrangement. Usually I will round up in order to get an even charge. I tip $1 for drinks and when I am with Mrs. mjcewl1284, it will be $2.
I tip valet people, car rental shuttles, room service "waiters" $1 per ride, service, whatever.
I tip pizza delivery people up to $2 per pizza I get or if it is a large order (over 4 pizzas-- at work) I'll go down to $1 per.
I tip cab drivers up to $2 per ride, $5 for a longer ride over 2 hrs. $5 flat for limo services.
I tip luggage attendants $2 per bag.
I tip parking attendants $2 if I drive my Buick. $5 if I take the Mercedes out
I tip barbers $2 per visit.
I tip my house-sitter (yeah weird I know) $5 per day she sits.
On tours if my tour guide did a great job, it would be $5 per day. Otherwise, $2.50 per day (round up)
I used to not tip housekeeping and when Mrs. mjcewl1284 found out for the first time I got a talking down to.

So they usually get $1/night I stay.
I usually give my mailman around $20 worth of gifts around Christmas time.
I gamble a lot. I tip Blackjack dealers $2/$2.50 (if $2.50 chip is used) per blackjack I get (and higher if they do pool tips). I will leave extra $1s for the dealer upon leaving the table as a tip. I tip Poker dealers (Texas Hold'em) $1/per pot I rake in and $2-$5 per pot over $150 that I rake in (I do NOT reneg on tipping for any pot I recieve). For exceptional dealing, I give them $1 when they leave for another table. I tip cocktail waitresses $1 per drink I ask for.
For tip jars I deposit change up to 4 pennies. I don't believe chain store establishments such as Starbucks should be using tip jars at all.
I think I might be missing something but I'll add it in when I think of it.