Cargo Bridge is a fun physics game in the style of games such as Angry Birds and World of Goo. The challenge is to build a bridge and test your construction skills.
Would be a fun game to introduce to students as an end-of-term activity. Works well on the IWB but can also be played on laptops.
Access it here: http://webstore.limexgames.net/cargo_bridge/index.html
Thanks to Nick at Fractus Learning for the link.