Came across this software, free for educational/personal use, which allows multiple mice use, which looks interesting for class room use.
It doesn't allow the multiple mice to be actually in use at the same time ... whoever left clicked last has control.
I tried a 2 handed paint shop pro drawing session... it worked ...maybe an "ambidexter" might find it useful.
TeamPlayer 2.0 Multi User beta
TeamPlayer 2.0 is the first commercial solution for working together on the same computer. Simply connect extra mice and keyboards to your usb ports, install the software and multiple cursors will appear on your screen.
Everyone works on one screen
WunderWorks' TeamPlayer allows you to work with 2 or more people on the same Windows PC at the same time.
For Business, Education or Home use
Work through your spreadsheets together, involve your students or just have fun with your kids. TeamPlayer turns any Personal Computer into a Group Computer. It's generic, so just click on an application and take control. Share your ideas knowledge or expertise with the others in the group.
Works with all standard input devices
Just hook up your mice and keyboards, add a digital whiteboard or tablets and start your group session.
http://www.wunderworks.com/public/home.aspx