Anonplus is a highly flexible framework for creating decentralzied applications which are targeted at users. Anonplus also offers a social network free from interference.
RTS2 is project to create an environment for control of a fully autonomous observatory. It is known to run about a dozen fully autonomous observatories. Its modular design allow easily addition of new devices (to the already huge supported HW list).
A geocaching query tool.
A PostgreSQL performance monitoring and auditing tool.