In what is one of the best case mods of the original Xbox that I've ever seen, user ghostavel over at Xbox-Scene has created a DVD-less, vertically-oriented, hdd-equipped, dead sexy version of the normally bulky console.
This master modder has completely done away with the DVD drive, instead adding an 80GB hard drive. All of the visual design was drawn in AutoCAD, and the plexiglass case was then cut by laser so, as ghostavel says, "everything is precise." He can even use interchangeable faceplates!
He's even gone so far as to custom-produce a miniature power supply for the unit, so I'd imagine the removal of the optical drive's power-hungry mechanism was quite helpful there.
The final product is almost ready, but even now, in its unfinished state, the thing looks awesome.

The Q Opinion on Activision/IW?
Listen Up 2009 Listen Up Awards
Eddie Inzauto Turning On My Sexy Lady
FilmPLOSION! Up Blu-ray Review
Brendon Lindsey When Game Journalism Gets Lazy
Pro Tip Pro Tip: Resident Evil 5: Lost in Nightmares
OneWordReview One Word Review: God of War
Head 2 Head H2H Deathmatch: Bobby Kotick vs. Major Nelson
Jason Fanelli Sex or Violence: Lesser Evil?
Tyler Cameron Do Achievements Ruin Videogames?
OLD SKOOL Ups and Downs of the 8-Bit RPG: Dragon Warrior
VS Node VS Node: Do You Want Files With That?
Mike Murphy Heavy Rain Has Revolutionized Videogames
Top 5 Takedown Top Five PS3 and 360 "Fails"
Dan Crabtree FOX News: The DS is for Pedophiles
Matthew Erazo BioShock 2: The Anti-BioShock
*jaw entirely falls off*
Microsoft should definitely hire this guy.