For non-programmer usage, you could do a load-balanced webserver/media server/home server. Cost wise you could launch your own retro Yahoo directory & search using a FW400 enclosure for storage(PATA internal HDD of the mini would be too old & unreliable or expensive to use an SSD).
At the moment I dusted off a old ITX Atom as a test setup for a web project, four spare HDDs= 1.4TB (2x PATA & 2x SATA)