modular video jockey software. The base visuals can be chosen from sources like video files or cameras. Then they can be modified by filters and mixers.
Draw Freely, Open Source vector graphics editor, with capabilities similar to Illustrator, Freehand, CorelDraw, or Xara X using the W3C standard Scalable Vector Graphics (SVG) file format. Supported SVG features include shapes, paths, text, etc
an OCR (Optical Character Recognition) program. It converts scanned images of text back to text files. GOCR can be used with different front-ends, which makes it very easy to port to different OSes and architectures.
a tool for compositing images. Given a set of images that overlap in some irregular way, Enblend overlays them in such a way that the seam between the images is invisible, or at least very difficult to see. Enblend does not line up the images for you.
a technique developed by Shai Avidan and Ariel Shamir for resizing images by removing the boring bits (content-aware image resizing as they call it). (see rsizr for a web tool that does the same)
a portable command-line driven interactive data and function plotting utility for UNIX, IBM OS/2, MS Windows, DOS, Macintosh, VMS, Atari and many other platforms.