Claire,
I just did a novel control program for a guy I met here at PLCS.net. He works for a company that makes those automatic flush valves that you see in airport and other restrooms. If you search the old files, I am sure you can find the thread. He needed a PLC program to test 8 flusher triggers at a time. Apparently he uses actual commodes, because he wanted a 5 minute delay between flushes to give the tanks time to refill....
I kid you not, this is an actual PLC application, and I wrote the program, and he is using it now. In fact he came back and wanted to add a graphical interface to the program, which I did. If you want a copy, I could post it if there is any need. It runs on an Automation Direct DL-06 PLC, best I remember.