Here is a Mac Mini built into a classic Nintendo Entertainment System. On top of that, there is a tray loading DVD drive cleverly built into the cartridge slot.

Here we have a classic Apple Macintosh SE/30 originally released in 1989 powered by a Mac Mini that is embedded inside the case. The Mac Mini is hooked up to the original 9" CRT display which gives it that retro look and feel.

This interesting Mac Mini mod is powered by batteries, making this a weird but interesting looking laptop. The Mac Mini G4 Portable includes a TFT screen, mini keyboard and trackpad. See the project here. 

Here is an interesting Mac Mini Modification. It's a 1942 Philco phonograph modified with a Mac Mini and a 17" touchscreen turning the Philco radio into a jukebox style media center. Music can be played through iTunes or Front Row.