Kids and Allowance: How Much Should You Give Your Kids?

I haven't instituted allowance in my house yet.  I have been teetering on the whole idea.  Don't get me wrong, I do reward good behavior in my house.  If E. has a good week in school and does his chores with out a fight we get froyo or a movie.  However as he is getting older he is starting to ask for thing that cost a lot of money.  So I am thinking it might be time to start giving him an allowance.

I was reading a Harris Poll this morning on this subject and this poll suggested:

These are averages, this poll was really in depth asking the different generations what they pay their kids.

4-9 year olds: $3.90 per week (OK I don't deal in change so $4)

10-13 year olds: $8.34 (I would probably just go with $10)

14-17 year olds: $15.60 ($15)

So this is what this poll says, I'm curious, what do you give your child for allowance?  What do you do to reward them?