I tried a system last year that I absolutely love and it requires very little work on my part. I got the idea from whole brain teaching. It is like a teacher/student game and I give extra credit or dexter credit throughout the day. You can watch a video of Chris Biffle using it at this site
http://www.youtube.com/watch?v=eBeWE...eature=related
I give chat time or music time at the end of the day for however many extra credit points my students have over and above the dexter points. Over the course of the year, I change the rewards and I keep a running tally of the extra points they have earned each day and reward them on Friday. The key is to make sure that you don't let the students win every day and especially don't let them win the first couple of days. Make them work for it. Make sure their behavior is exactly the way you want it before you let them win. It's awesome because, it is so universal. I give them feedback everytime that I give them points so I can use it to work on all kinds of things.