What to do with an old PC?

Sorry if this isn't the right forum but I didn't exactly know where to put it.

Well I've recently upgraded my computer and now I have an entire extra computer lying around. I've been trying to think of some good ideas on how to use it but I'd like some opinions and more ideas.


i3 550 
Amd Radeon 5670 gpu. Can't get anymore specific, it's old but it still performs decently. 
An MSI mobo 
4 gigs of 1333 ram

Play around with various Linux distro's, make it a torrent box, make it a media server, sell it, give it to a poor student in your neighbourhood that needs a pc for school. Heap of options.

You could try to sell it by parting it out? Nas, small game server, PF sense box. Just some ideas.