Refined GitHub - Browser extension that makes GitHub cleaner & more powerful
Awesome Viewer - Visualize all of Github's awesome lists
GitZip - Download or create a download link for a GitHub project folder/sub-folder or file.
Viz - Visualize GitHub's newest, most popular repos
Zube - Project management for developers.
Megabits - An 8-bit, Pokemon-like MMO in real-life (iOS)