I got an allowance when I was growing up. It started at $5/week when I was in middle school or so, and was increased periodically as I got older (and went out to socialize on my own more often). When I graduated from high school, I was getting $20/week.
Interestingly, given all the stories above, I didn't actually have to do anything in order to get this allowance. Sometimes, I kind of wish my parents had made it contingent upon my doing some household chores, because I'd probably have learned to do them more consistently if they had. But on the other hand, my "job" when I was a child was to do well in school. For whatever reason, my parents never actually assigned any specific chores to me (although I was expected to do things when they asked me to). I didn't get paid for good grades, like some of my peers did, though. The allowance was really a separate entity unto itself.
My allowance money had to pay for any meals out (including lunch at school) that I did not have with my parents. It also had to pay for my entertainment, and anything that I couldn't justify as a "need." So my parents bought my basic clothes, but would sometimes tell me that certain things had to come out of my allowance if I really wanted them.
However, when I started college, I no longer really got an "allowance." My parents paid for my living expenses all the way through, but started giving me more of a lump sum that was supposed to cover everything they didn't pay to the school directly. So I started having to buy basically all of my own clothing, pay for gas, pay for my cell phone (I didn't have one of my own before college anyway), and of course pay for all of my entertainment. It was never really a set amount of money -- they would give me some amount they thought was reasonable and we'd discuss about how long it was supposed to last me, and if I asked for money before that reasonable length of time had passed, I'd better have a good reason.