I always made my kids sign-up and complete the local library summer reading program. I felt like it was good to keep them practicing those reading skills, plus they got coupons that we could use over the next several months after fulfilling the criteria (books read and library visits).
Yes, they even did it through their senior years. Tiffany and I even complete the new adult summer reading program last year, which reminds me, I need to check into it again.
Here are some fun looking activities to do for reading this summer. Although the printable is rather bland, it is an interesting summer reading scavenger hunt. This is a direct link to the printable pdf used by some school/teacher. You can use it to come up with your own requirements and rewards. And here is another. [2018 update: this last one is no longer available.]
On this webpage when you scroll down the page, there are two pictures of bingo cards. The one on the left is the reading bingo and the one on the right is summer fun bingo. If you click on the card itself, it will open up the pdf which you can then print. They look pretty neat. She has some good ideas on how to use them cooperatively and individually. She also has links to a camping scavenger hunt bingo and a road trip bingo at the bottom of the post. (All are free.) [2018 update: these are now available with email sign up.]
Although this next suggestion seems to be an old post, it has some neat suggestions they call book-tivities. They also have some suggested book lists for different ages/grades.
I did find one more, that looks to be for older individuals. I have never heard of this author before so, you might want to do a bit of research before entering, but it is definitely interesting. [2018 update: the prizes are no longer available but it could still be a fun way to choose books to read]
I hope these will be beneficial to you and your children this summer.
Until next time, God bless,