tEp's backdoor webserver is running on an atMega128 microcontroller with a TCP/IP stack. The hardware is some gorgeous open-source hardware called the ethernut, which runs nutos, a nice multithreaded operating system for 8 bit AVRs.
The actual server page is here(tEpnet only!)
They say necessity is the mother of invention. I live on the fourth floor. When someone's ringing the front doorbell, I don't want to run down four flights of stairs just to answer it. This webserver is driving an electric striker plate in the back door of tEp, which retracts when the correct password is entered. The webserver also interfaces to a DDR pad outside tEp, which allows people to dance a combination to enter the house.