Wired has a really awesome gallery of tiny, tiny computers. You can't help but love a full computer crammed into something the size of a box of matches, can you? Sure, some of these aren't really at that small (Mac Mini? Come on, dudes.), but there are some pretty awesome examples of wee 'puters in here. Although they did forget a pretty tiny computer that would have fit well on the list.
The Gumstix Linux PCs are, as the name states, about the size of a stick of gum but manage to function as full-out computers. They're a hell of a lot smaller than a Mac Mini to boot. But hey, one missing computer doesn't ruin the whole gallery, which you should definitely hop on over and check out. [Wired and Gumstix]