Treats for positive reinforcement
I'd like to come up with new things. I alternate with a fun food item, sticker, extra time on his Nintendo DS, mazes, word finds... Sometimes, if it's a really important goal, I'll give loads of little ones (little toys and stickers, his choice out of the bucket), and when the big goal is accomplished (for instance an entire school week of working at something, and he was able to do it 4 out of 5 days), an additional big treat, e.g. rock climbing for a day.
What do you use?