rmachine is a simulator for register machines (in the context of complexity theory), complete with a GUI and a Python module to be used in your programs. The machine ("RAM") is equal to Turing machines in its computional power. It has theoretically unlimited memory (but is limited in practice by your computer's memory).
MUSoSu is a free software project for playing, solving, and generating Sudoku games. It is written in Java and emphasizes both solving Sudokus simulating methods used by hyman solvers and generating Sudoku problems that don't require trial and error methods to be solved. MUSoSu is partly themeable and platform independent.
Response is a set of tools to handle automatic email responses, also called "Out of Office", "Vacation", or "Autoreply" messages. Response tries hard to do that the correct way, i.e. not responding to messages that should not be responded to. All of the validation code can be easily modified to suite your needs, but the project tries hard to ship sane defaults. It is designed for many virtual users and multiple mail servers, but works just fine for small deployments. Configuration and response state is stored in an RDBMS.
ParaDB is a Web-based application designed for use by ghost hunting and paranormal research organizations. The software consists of a Web-based interface for case management, client relations, and investigation reporting. As the name implies, all data is stored in a back-end database, allowing one to easily access, search for, and correlate data.