Browsing a couple of new sites, I've come up with perhaps an interesting new way to practise comparitives and superlatives. Let's call it Hot or not? after the original website of this kind.
Do you remember Hot or not? It was really big a few years ago. The idea is that you upload a photo of yourself, or more probably a friend, and users rate the attractiveness of the person in the photo on a scale of 1 to 10. Ten is 'hot'; one is, well, 'not'.
http://www.cutelittlekittens.com/ has a lot of super-cute little felines, especially in the section labelled "cutest kittens", and it wouldn't be too hard to print out a copy of a few of them and have learners vote on which of two is cuter than the other, and which is the overall cutest of the bunch.
For less sensitive classes (read: ones that won't get offended judging people), there are lots of pictures of guys and girls over at http://www.hotornot.com/ just waiting for your learners to tell them who's better looking than who, and who's the most attractive.