I've been working on quite a few new projects recently and have some Harry Potter themed things in the works, but I've just completed my first RetroPie based project, the ARCade Reactor. It's a retro gaming system that's powered by the Raspberry Pi. The ARCade Reactor name is derived from Iron Man's Arc Reactor, as my paint scheme is Iron Man themed it seemed appropriate (and to be honest my girlfriend came up with the name, so kudos to her!).
It has support for over 20 different systems, including the Playstation, N64, Super Nintendo, NES, Mega Drive, Master System (Genesis), Atari, Amiga.. it's basically got my entire childhood covered, so cue the nostalgia. Built inside an original NES console enclosure, you can play with a Wireless PS3 controller, a wired Xbox controller or pretty much any USB gamepad, but for that extra touch of authenticity you can even play with the original NES gamepad. It also incorporates the Kodi home theatre software with an internal 1Tb Hard Disk to store all your favourite films, TV and music. Check out my ARCade Reactor project page for more info.
You may also recall one of my previous projects, the Touchscreen Display for the PiKon 3d Printed Telescope. My touchscreen has been mentioned in a Make Magazine article featuring PiKon creator Mark Wrigley, check out the online version on Makezine. I've also created a Lite version of the touchscreen, this one excludes the battery and additional buttons, making it a much cheaper and easier project to re-create, check out the build on Instructables.