There is one school of thought that allowance shouldn't be tied to chores, the chores are something that we do because we're a family, we live in the house together and we want it to be a nice place to be.
Our children are expected to help around the house, they keep their own rooms cleaned, they take turns making lunch (depending on who has a busier day, etc), they do other things when asked and are expected to do it without complaint.
The allowance is nominal, $1 at 6 years old, $2 at 8, $3 at 10. At 12 years old, allowance goes up to $10 but they are expected to save $5 of it. At 14 it goes to $12, still saving half. Our 13 year old now babysits so is earning extra money, our 15 year old works a few hours a week with my husband (we have our own business) plus he refs soccer games during soccer season.
We don't just hand them money for what they want, some things they need to save for, the things they need we provide for them. Their allowance is 'mad money'...money to save for what they want, pay their way on youth outings, etc.
Our 8 year old just finished saving $55...he saved his Christmas money, birthday money, allowance and has been saving pennies for a few years now. He bought himself an aquarium today and is so please with it as it took a lot of effort for him to save that much money.
Anyway, I think amounts depend a lot on what they are expected to do with it. We homeschool so there are no lunches to buy, we buy what clothing is needed, but the older children are now also buying some things that they want as well.