VidCutter is an open source video trimming application that makes it easy to extract one or more scenes from a video clip and combine them into a new video.
Simply load the video file and mark the scenes you want to extract with Clip Start/End to add them to your clip index. You can re-arrange the order of the clips if you like and then save them as new video.
VidCutter will output a merged video file of all your clips, and an additional video file for each individual clip.
A basic tool which is what I needed - however its big benefit is that it handles a wider range of formats which products like realtrimmer for instance cannot cope with.