I used it last year and it was awesome...the kids loved it.
I made a 100s chart on the computer and laminated it... The kids could get numbers for various things. I had a cup for old numbers and new numbers. When they got a number, I picked the number from the cup and colored the corresponding number on the paper with a vis-a-vis.
My number system was:
1 number for:

none of the kids changed their cards today

everyone turned their homework in today
2 numbers for:

Getting a compliment from a teacher, principal, or another staff member (like "Wow, your class is being very quiet in the hallway).
3 numbers for:

Good behavior at an assembly

Good behavior at a field trip
4 numbers for:

A good note from a substitute teacher (I used to sub, so this is a big deal to me)
We voted on a prize for each time (no homework day, pajamas day, popcorn and a movie) and when we got 10 in a row, they got the prize.
They love it and I only had to give out 3 prizes throughout the year because it really takes a long time to get 10 in a row.
