If it has a Ethernet card, you could run some server programs on it. I made a LC III into a LAN Mail and DNS server. (Both programs were made by Apple.) You could also make it an IRC server.

I also had made it so it could boot up without a monitor, keyboard and mouse. I just made an apple script file to start up the programs in order. Then play a sound file to indicate when it was done. I used a db-15 to vga-15 adapter to get it to work without a monitor.