Thought I’d start a thread where GNOME users can mention extensions that they find particularly useful. Sifting through them on the site is a bit of a chore.
I’ll throw a few out there to get started:
Creates a menu of your installed extensions, allowing you to enable/disable/configure them from a taskbar icon.
Allows you to connect and do a number of things with your smartphone. My understanding is that it is essentially a GNOME wrapper for KDE’s extension.