It kind of depends what all you think is fun! If there were PLENTIFUL "FUN" jobs - everyone would want one! lol
How about walking dogs? Most kids like dogs and it's not hard to do.
Offer to House Sit for vacationing neighbors. That may include things such as collecting their mail for them, watering house plants, feeding fish, feed the cat, walking the dog, etc.
Good Luck! =)