Real-time, web-based gaming for distance learners?

I was thinking it would be great if we could somehow rig up a web-based, real-time, lock-out buzzer system so that our students from all over could participate in a virtual Jeopardy tournament. In other words, I could send a url and perhaps password to each participating student and the page would then display a simple button that acts as a buzzer in real time.

We could then display the categories and scores and the first student to buzz could speak answers using our Elluminate virtual classroom software.

Could even do a tournament on info lit skills and knowledge, for example.

I did a 2 second search for such web buzzer tech but didn't find anything - will have to check further into it. Anyone doing anything like that out there? Are the logistics possible?