Py-Lepton is a high-performance, pluggable particle engine and API for Python. The engine is designed to be very flexible and does not rely on any other libraries directly. You can use it either with OpenGL (via pyglet or PyOpenGL), or with pygame by selecting the appropriate renderer. Examples are provided using pyglet and pygame. Note that this is in an alpha state, so expect the API to change somewhat in future releases.
Gimp User Filter is a work-alike to Adobe's Filter Factory. It is a generic image processing plug-in that can be used to create new filters for The GIMP without having to go through the process of learning about The GIMP's SDK. Many freely available filters that have been created for Filter Factory can also be used with this plug-in.
Seamstress is a portable library that implements Avidan and Shamir's seam carving technique for content-aware image resizing. Seam carving works by removing the "boring bits" from an image, so it can change the aspect ratio of many images without changing the shape of the objects inside.
Tioga is a Ruby library for creating figures and plots with high quality text and graphics in PDF format. Text is processed directly by TeX (not an emulation), and the graphics covers a broad range of PDF features including images, curves, clipping, and transparency. Tioga is relatively easy to use, complete, and well documented.
CADTools is a modern 3D computer-aided design (CAD) and manufacturing (CAM) toolkit. The aim of the project is to develop an easy-to-use parametric, feature-based solid modeler with a generic geometrical constraint solver sufficiently robust for real-time mechanical simulations over complex assemblies.
FreeSG is a portable, high-level 3D engine with an emphasis on generality. It is designed as a component to be integrated, as opposed to an application framework. Its goal is to support applications ranging from small 3D games running on portable consoles to large simulations that must be rendered photorealistically using fourth-generation graphics hardware.