Ravec:  a 3D evidence grid library, with uniform array and octree backends.

FUSE for Google Drive: also includes a simple rsync-like tool.

Passe-partout: an implementation of transferable virtual property using the bitcoin blockchain. 

[background photo:  54 images captured by QuickCam Pro 4000 in prime focus of 12" Meade Lightbridge, stitched with Hugin, light cloud conditions]