Thought I'd pass this link along to you... Active Allowance is a wonderful website that offers free chore charts that you can edit and change to fit your family's needs. It offers ideas on incentives, appropriate chores/age of child. It also encourages the basing of allowances on responsibilities that your children perform.
The Basic Membership is free (this is what I use). Any additional features are under their paid membership rates which are charged on a monthly/yearly basis.
Hope you find this helpful!