ffmpeg : Public Domain Relay

ffmpeg is a powerful tool for command line video, audio, and image processing (centered around images and audio as they relate to video).

Here's some things you can do with it

Video to GIF

$ ffmpeg -ss 0.3 -t 40 -i input-video.flv -vf \
  "fps=10,scale=1920:-1:flags=lanczos,split[s0][s1];[s0]palettegen[p];[s1][p]paletteuse" \
  -loop 0 output.gif

Arguments:

-ss start second
-t end after X seconds
-y means overwrite the output file without asking

Notes:

scale=1920 lower this number to lower Y (I think?) resolution, lower will give you a smaller file size
fps=10 lower this number to speed up, number of frames per second, also will decrease size of output file

Crop video

$ ffmpeg -i putin-on-ritz.mp3 -ss 00:00:43 -t 00:00:57 -async 1 cut.mp3

Combine with image

$ ffmpeg -loop 1 -y -i putin-on-the-ritz.jpg -i cut.mp3 -shortest out.webm