Mac Mini = Digital Signage Heaven
Mac Mini's are great for Digital Signage (Think Sedna Presenter, which so happened to power the signage at Macworld), Kiosk's, DVR/Apple TV replacement, Render Farms, File/Print Servers and just about anywhere where space is limited or where you need to embed a computer. If Apple would target those markets the would fly off the shelves faster.Some of us just want it to be kept reasonably up-do-date.
Whatever else the Mini is or isn't, what it is is a desktop(*) Mac that is (or would be...) ideal for anyone who already has a perfectly good screen that they still use (or for those who favour matte) and doesn't want to fork out an extra couple of hundred pounds/dollars for an all-in-one or laptop with an unneeded screen and extra footprint.
Whether for HTPC, gaming or (like me) just general computing, there are many of us who simply need a non-outdated machine that does not have a built-in screen.
(*) In that, regardless of components, it sits on or by a desk and runs off the mains.