btar is a tar-compatible archiver which allows arbitrary compression and ciphering, redundancy, differential backup, indexed extraction, multicore compression, input and output serialisation, and tolerance to partial archive errors.
s2png converts files with any kind of binary data into valid PNG images (e.g. for hosting on the Web) and back. It supports encrypting the output.
A mod player library.
Easy booking of stays by time and date with different languages and currencies.