Many restaurants offer "kids eat free" deals, but the problem is nobody knows where those places are and when they are offering those deals. There are several websites that eliminates the guesswork. Two really good ones are listed below.
www.mykidseatfree.com has a state by state listing of over 5600 participating restaurants covering every night of the week.
www.kidseatfor.com has a great calendar that shows all the free and cheap kids deals based on zipcode.