I use treasure hunts, where you put sets of questions up on the wall, and have the kids find the answers. Each set is for a different group of students. The questions are tailored for the group. It just occurred to me that it could be done on the computer as well.
Perhaps setting up a form in Google Docs for each group, then have the kids answer. It ends up being a review for a test, and if you have them put their name in, you know where they are at. You could also set it up as a webquest or website.