Shayde has written a convention registration system called CONGO which is right flexible and designed from the ground up to be extensible and scalable. He's written a couple of pieces on the building of CONGO
The CONGO technology has two interesting bits from my view point, and those are the articles presented here. First is a logistical article on how Shayde built his server cluster for a very reasonable sum, and the second is a reasonably technical piece on how to convert an iopener into a useful standalone Xterm.