Kelly Strahm - This is a site that has numerous powerpoint review games.  Some are free and some you need to subscribe to.  There are numerous free ones that can be used "on the fly".  They require no advanced prep other than a series of questions or problems (these would be easy to come up with in short notice).  Many are team games and there are a few that could be used as an "every man for himself" kind of game.

http://jc-schools.net/tutorials/ppt-games/

Gretchen Reichow -  

A free world-class education for anyone anywhere.

The Khan Academy is an organization on a mission. We're a not-for-profit with the goal of changing education for the better by providing a free world-class education to anyone anywhere.

All of the site's resources are available to anyone. It doesn't matter if you are a student, teacher, home-schooler, principal, adult returning to the classroom after 20 years, or a friendly alien just trying to get a leg up in earthly biology. The Khan Academy's materials and resources are available to you completely free of charge.

www.Khanacademy.org

The Google Science Fair challenges students aged 13-18 to carry out a scientific investigation into a real-world problem or issue that interests them. The competition asks them to carry the investigation forward through rigorous experimentation, recording and conclusions.  There’s a whole raft of resources to support you in the classroom and help spark your students’ interest. You can even host your own mini science fair!  Here you can download everything from a competition overview presentation to detailed Lesson Plans. You’ll also find key tips, rules and checklists to take the hassle out of explaining the essential small print to your budding scientists.

http://www.google.com/events/sciencefair/index.html