What to do with old hardware?

So I have a bunch of old junk hardware. I don't know what to do with all of it. This is basically all of it: Pentium D @ 2.8GHz, ATI Express 200 Series, 2x512MB DDR2 RAM @ 960MHz, Xubuntu 12.04, Generic HP Case, Another old P4 machine, and a random Sempron machine. It's not really worth selling on eBay because of shipping. I was thinking about just taking it all to a pawn shop. Is there anything productive I can do with all of it?

You could turn it into a kickass router with pfsense. You'd probably have to buy a compatible network card with enough ports though. 

Network cards are cheap though right? And even still that would leave me with two other working computers.

Yeah, network cards are generally pretty cheap. I'm pretty sure you'd just have to get one with multiple ports on it so you could plug all your computers into it. Logan did a video on pfsense a while back. You might want to check it out.