Launchball is an online activity from the British Science Museum. You can create a sort of video game, title it, and then email the url to be posted on an online journal or blog.
I’m looking forward to trying this with my English Language Learners. There’s a fair amount of vocabulary that is needed to design the game, and I’m amazed at how quickly my students can pick that up when it’s video-game related. Posting this url on a site, along with an explanation they would write about how to play it, would be another added language development activity.