http://heroinewarrior.com/cinelerra.php3

Cinelerra does primarily 3 main things: capturing, compositing, and editing audio and video with sample level accuracy. It's a seamless integration of audio, video, and still photos rarely experienced on a web server.

http://www.celtx.com/

Celtx is the first, cross-platform media application that provides support for the entire pre-production process. It runs on Mac, Windows and Linux.