Log into multiple accounts on the same site simultaneously.
A republishing of the super-handy MultiLogin extension with the connection back to a home server removed and the goal of becoming completely open source and safe to use.
WARNING! Numerous users have reported that this extension does not work with Facebook and Google services. If you're looking for something along those lines, you should probably keep looking (or head to Github and open a pull request).
Want to enhance this extension? Make a pull request!