Incentives aren't really necessary when it comes to reading in our house, BUT since they will be reading anyway I have no problem signing the forms so they can receive the rewards.
Barnes&Noble Read any 8 books and record them in the Reading Journal take the reading journal into your local store and choose a book from their list.
Tennessee Smokies Baseball Read 10 chapters or books per level, reach level 5 to attend the end of summer picnic event at the ball park! If you don't live in East Tennessee, check your local minor league baseball team to see what they may be offering for kids this Summer.
Scholastic Read and log minutes all summer. Take weekly challenges and earn rewards. Help set a new reading world record!
BJU Press Ages 4-17, log 40 days of reading to be eligible for great prizes, including a Kindle Fire!
Pizza Hut Book it! Read 5 books to be eligible to win a prize!
Don't forget to check your local Library, ours always has a GREAT Summer program for all ages!
I'm sure there are more, these are the ones we've signed up for so far.