C.L.
Good for you! I looked on Love and Logic's website and they don't have anything free I could find pertaining to amount for a 7 year old. He definately should not be paid to do the things that he should do anyway, that's the problem with half the kids these days, they expect to get paid for everything even if it is their responsibility.
The Love and Logic school of thought was they can do "extra" around the house to earn money that are not tied to his responsibilties. You could give him $15 a week, but you also need to start him out right by taking applicable "taxes" out of what he makes as well. It helps teach fiscal responsiblity as well. You could always put that money away in a separate IRA for him or something.
Good luck!
C.