We recently bought this sticker chart for memorization of Juzz Amma, my kids like the idea. You can buy them from Cii stores in Lenasia, Johannesburg or alternatively buy online from here
This is what it looks like
We also have the following progress sheet for each day of working for memorization. I like to give rewards on working for a number of days rather than on completing the sura, as memorizing Quraan is from Allaah but putting effort is in our hands, and i like to reward for things that are in our control. You can download the progress/reward sheet from here. It is in MS Word format so you can customize it easily.
Here is what it looks like