A Raspberry Pi — All the power of a 10 year old desktop in a tiny little box (box not included). And with the added enjoyment of a bare bones Linux desktop. Of course they updated it to be 6x more powerful about a month after I got mine as well.
Of course the real fun starts when you start actually building things with it. And it is already working as a basic photo frame using the TV as a display and serving pictures straight from the Linux server via a smb share.
So many things to do, so little time.