LiVES is a simple to use yet powerful video effects, editing, conversion, and playback system aimed at the digital video artist and VJ. It runs under Linux, BSD, Mac OS X/Darwin, IRIX, and openMosix. It is frame and sample accurate, can handle almost all types of video, and is fully extendable through plugins and the included plugin builder tool. It can also be controlled remotely using OSC.
Converseen is an image converter and resizer written in C++ with the powerful Qt4 libraries. Thanks to the Magick++ image libraries, it supports more than 100 image formats like DPX, EXR, GIF, JPEG, JPEG-2000, PhotoCD, PNG, Postscript, SVG, TIFF, and many others. Converseen allows you to convert, resize, rotate, and automatically flip an unlimited number of images. It can save you time because it can process more than one image with one mouse click. It features a very simple user interface without strange options.
FF Multi Converter is a simple graphical application that converts audio, video, image, and document files between all popular formats, using and combining other programs. It uses ffmpeg for audio/video files, unoconv for document files, and the ImageMagick library for image file conversions.