portable GameCube mods before, but the CCube (Compact Cube) built by one Jonathan Shine may be the smallest. Created using a GameCube, an old answering machine case, plastic cement and many coats of paint, the project took fifteen months to complete -- much longer than the original two weeks John had estimated.
You'll find a video of the CCube after the break (skip to 2:20 for gameplay). With the disc drive actually located outside the case, it's worth noting that it's a tad on the noisy side, but impressive nonetheless. Then head over to the Mod Retro Forums for a detailed look at the CCube's construction.