Previously I emailed around about a useful site for creating image-based labelling quizzes: purposegames.com. This site is excellent for subjects like Biology, Geography and PE and I'm sure can be useful to any subject area with creative use!
There are many good quizzes already available to use and it is very easy to create your own - particular the 'Dot quizzes'. Games can be collected into playlists or included in Tournaments to get a competitive aspect.
The screenshot shows an example of how the quizzes are presented:
You can check out the playlist I have created for AS Applied Science, including the example above: HERE. This playlist consists of Dot quizzes created by me or found in the existing library.
Here are some examples of the other types of game you can find or create: