EnKoDeur-Mixeur (EKD) is an open source software which makes videos, pictures and audio post-production. It can be also used to convert videos in many formats. It is written in python and use the PyQt4 bindings.
CthughaNix is the reincarnation of Cthugha-L, a Linux port of one of the first audio visualization software packages, known as "An Oscilloscope On Acid".