We started giving our children allowances a few years ago when they were 4 and 6 (they're now 6 and 8). It's been one of the BEST things! They've not only learned how to count money, but how to make choices and appreciate things. I don't buy them toys any more (just at Christmas and birthdays). If they see something at the store that they want, they check how much they need to save to get it. I don't hear any whining any more because they know I'm just going to ask them, "so how much do you need to save for that?"
We did not connect the allowance to chores--they do chores because they are part of the family. But for extra big jobs around the house, they might earn extra money, by arrangement. And they take care of sorting cans and bottles and get to split the recycling money.
At the start I told them that the purpose of the allowance was to teach them to be wise with their money and make choices. Just like how mom and dad have to choose whether to buy food and gas or a new tv. We talk about how mom and dad pay bills for the house and how important it is to know how to use your money well so you don't end up with a new video game but no food.
Here's the way we do it at our house:
Each week they get half of their age as allowance. So the 6 year old gets $3 and the 8 year old gets $4. Out of that (I have it figured out for them and they get correct change), they put 10% in their charity (tithe) bank, 50% in their savings bank, and 40% in their spending wallet. I make them wait until their savings bank has $10 before they take it to the store. They can choose a worthy cause for their charity money (we give ours to our church).
So each week my 6 year old has $1.20 in her wallet to spend. It doesn't sound like much, but it's enough to buy something from the dollar aisle, or to save to buy something a bit bigger the next week. (After two years she is now finally able to keep it from burning a hole in her pocket!) The idea is to have an incentive to save. There is no good reason that they should have enough to buy a new big toy each week, and they wouldn't appreciate it either. But the things they have saved and waited for--those they value as special.
The allowance has turned out better than when I just gave them dollars here and there. With an allowance, they know what to expect and can plan how to get what they want.
My favorite article about allowance is this one:
http://www.crown.org/LIBRARY/ViewArticle.aspx?ArticleId=343
I'm all for helping our kids learning money management, and we can teach them even when they are very young. Hope you find something that will work for your family. Best wishes!