The Taoist text.

A Java image library, the includes support for Gif, Png, Bmp, Tiff, Jpeg, etc. Includes support for extracting, parsing and applying ICC Profiles. Reads and writes images (except Jpeg). Pure Java, Open source.
News: Sanselan is moving to Apache! More info here.

Python annotations that provide type checking, etc. Open source.

Strips unused classes from Java jars, making for smaller distributions, faster load times, etc. Open source.

Reads & writes music file metadata in the ID3 format. Pure Java, Open source.

Performs text transformations on text files. Open source.