LosslessCut is a video editor for lossless trimming and cutting of videos without losing quality. Simply load the video file and use the start/stop cut marks to specify the section that you want to cut. Click on the cut icon and the marked section will be exported to a new video file without any decoding or encoding.
You can also use the program to take a quick JPEG snapshot of a scene. LosslessCut uses ffmpeg (included) for doing all the grunt work.
This great little program allows me to remove commercials from recorded TV. I only wish that it was possible to select multiple portions for removal at a time rather than only being able to select one portion at a time to be saved without the rest.