It looks like Single Site Browsers (SSBs) are dying out, at least on FireFox.
If you are non familiar with SSBs Fluid is the obvious choice on Mac OS X. SSBs are helpful since they give you a whole separate site (or task) focused process running just one (or several related websites). This is good because:
- Command-tabbing to apps is possible.
- The main web browser can be restarted independent of one particular site e.g. Grooveshark or Pandora can keep playing your music while Firefox restarts.
- Separate cookie store to keep you logged in and prevent other sites from peeking at cookie they don’t own.
Unfortunately there are fewer SSBs today than a few years ago. The Mozilla (Firefox) based SSB Prism was handed over to Salsita Software and became WebRunner which was subsequently discontinued. A similar project, Chromeless, was started within Mozilla but also discontinued.
This leaves anyone looking for a Firefox SSB to try hacks or used SSBs based on other browsers.