Some friends of mine were having the big problem of wanting to control their student's computers in the classroom.
The solution is free and easy and comes with Ubuntu Linux 9.10:
iTALC
iTALC is a use- and powerful didactical tool for teachers. It lets you view and control other computers in your network in several ways. It supports Linux and Windows 2000/XP (Vista support will come) and it even can be used transparently in mixed environments!
In contrast to widely used commercial equivalent software, iTALC is free! This means you do not have to pay for expensive licenses or things like that
