Cult of Mac points us to one enterprising hardware modder who has converted the base of his iMac G4 into a round wall clock. Take a look above on the left for the final result of his Dremel-sourced endeavor. This Apple fan from Japan was also kind enough to post photos of his DIY adventure [Google Translate link]. Check out another image below; the aluminum really pops on the dark wall.
Additionally, it seems that the inspiration for the iClock came from another Japanese modder who converted his PowerMac G5 into a functioning timepiece as well. Seen at the top on the right is the completed product. When all is said and done, it seems as though the PowerMac is still usable as computer. This qualifies the creator's work to be considered a "case mod" rather than an all out butchering -- which is ideal because a chopped Mac is a sad Mac. The PowerClock owner also posted in-progress shots of his work [Google Translate link].
I tend to fall in the camp that favors "software" modification, believing that for any piece of computing hardware there is some flavor of Linux that can breathe in new life. Unfortunately, however, sometimes Macs and PCs alike simply bite the dust and are only good for conversion into clocks or lamps.