Blarg. That was a practically useless machine when it was introduced. And this from an old Mac user.
Well let's see. If you can scrounge up an old free copy of EIMS (Eudora Internet Mail Server) you could use it as a spam relay. You could pick up an second ethernet card, install IPNetRouter and use it as a NAT/DHCP/Router. But a Linksys box is cheaper and easier.
Most of the Linux variants for Mac boxes want a PowerPC chip. That box you've got predates the PPC. You could try
this version of linux which runs on the older 68K chips.
Honestly though, it's a damn fine doorstop. I just dumped my old Quadra 800 which was a far better machine than you've got there. I couldn't even sell it at a garage sale with software and games.