Volker's and Caleb's answers are boringly destructive. How about making a macquarium?
I don't think the 6100 is the right shape for a Macquarium mainly because it doesn't include a built-in-display.
But if you want to know what can be done with a *really* old Mac, we have a working Mac SE/20 in our server room. It has 4MB RAM, 40MB HDD (upgraded from a dual-internal-floppy). It has had its OS upgraded to Mac OS 7.01.
It is still in constant use as a telephone-call-logger. It it connected to our PABX system via a null-modem RS232 cable. It runs a custom-written hypercard stack which parses the serial-port input into human-readable format, and then uploads the data (using afp over appletalk) via its 'localtalk network' port, through a 'localtalk-to- ethernet' bridge and into a Filemaker database running on one of our more recent servers.
It really does look quite odd, this 20 year old machine sitting there between all this other more up-to-date equipment, but still going strong. I wish I had a digital camera with me at work today so I could take a pic to show you all ;-)
It just goes to show - they're not useless until you give up on them! Cheers, Pete
