Topic Database provides a standardized context for plain text databases which can be read and edited in most text editors without difficulty, and easily parsed programmatically as well. Example parsers are available in several languages.
PySnippy is a simple GNOME desktop application for managing your snippets online (at snipplr.com) and offline from an SQLite database.
Containers using Linux user namespaces.
A 2D platform game with a persistent world.