(you can click/tap/whatnot to dismiss this!)
This website generates simple square firework-resembling things. It also has a few different extras to try and be more awesome than can be.
If you add #fractal to the end of the address bar then the firework's particles will also explode as fireworks. I'll have to warn you, that is a very easy way to make your browser crash!
Add #fadey to the end of the address bar to get the fireworks to draw trails instead of just disappearing, however there's a slight problem with leaving gray trails with that.
The last and most important extra is that you can load your own image as a background, the only problem is that it has to support Cross Origin Resource Sharing. imgur and dropbox do! Just use #image=http://i.imgur.com/hEasw.jpg or any other image link in its place.
You can combine the above extras by putting a comma between them, for the sole exception that the image=..... extra has to be the last one in the list. So #fractal,image=... works just fine.
Happy New Year!