Animated GIFs

Google+ has a nifty feature -- known as 'auto awesome' -- where it detects runs of photos which may be compiled together into short animations, automatically creating these animations for you.
If uploading all your images to Google+ to create a few animations seems a little excessive, you can create your own using ImageMagick:
convert -resize 1024x1024 -delay 20 *.JPG output.gif
Update: ffmpeg
can do the pretty much the same thing for movies which are a far more efficient format but require a little more work to embed:
ffmpeg -r 5 -pattern_type glob -i '*.JPG' -c:v libx264 -pix_fmt yuv420p output.mp4