We have a kind of combination thing here -- the library has its own, but it also accepts the school's sheet. The school's sheet wants 20 minutes a day, five days a week, and each month's reading log gets an entry into a drawing for prizes. The library asks you to sign up for your own goal, and then has prizes along the way and drawings at the end for bigger prizes.
I'm totally with ultra and DeeDee here -- I find it impossible to get myself to bother with logging things, and eventually at the end of summer we fudge the whole thing. Assuming they have actually been reading. I allowed DS10 one log's worth last summer because he read some, but not a lot, but DD7 got all of them because she reads all the time. I just can't manage to fill things out and keep track as they go, when I'm at work all day. This year I told them it's their own responsibility to fill things out, and you can guess how well that's working out.
You would think that being able to turn in each two weeks' log for free ice cream at the local store would be enough to get them to do it, but no.
