Hopefully by now, almost all of us use Texture Packer (or similar) to pack assets for our games. However Marcelo Lv Cabral found a need to do the opposite: extract the frames back out of a texture atlas, into single PNGs. This is actually a feature that Texture Packer itself doesn't support, so he packaged it up and released it as open source. Nice one :)
There's even an online version created by EneaGames too.