BlackBug is a JavaScript framework for creating particle animations with the HTML5 canvas element. Particles can be used to create cool effects, like rain or snow falling down, bubbles, swarms of insects, etc.
BlackBug is released under the GPL. You can modify the source code and redistribute it as you please as long as you release it under the same license. I would appreciate if you gave credit back to this site, and if you shared what you've change, but the choice is yours.
Here are two examples of what you can do with BlackBug:
Go to the GitHub page.