I must recommend this great site What2learn.
This site allows you to make simple but fun games based on any subject you like. The games are kept online and you can provide links to them or even embed them into your own blogs. This service is entirely free of charge and both teachers and students can sign up. The teacher can make the games and bookmark them for students or have a group sign in and have the students design their own games. The site is easy to use and the games very quick to develop.
I have embedded my first one below. There are a couple of truncated questions as I wrote out the full definitions as given in the Cambridge 0610 2010 IGCSE Biology syllabus. However I think it is still okay to use. I plan to do a full set of games covering the definitions (using a variety of games) so keep an eye out for them.
The link for the game is: This has now been removed due to the fact it makes a daft noise when you log in. Email me if you want the html code to embed it into your own website.