Post-Obama changes[*] in Firefox extensions internals have changed the way Tabhunter behaves. It currently can't run as a standalone window, but shows up as a popup anchored in the main toolbar. You can get it to popup by pressing Ctrl-Shift-T on OSX, Ctrl-5 on Windows and Linux -- With newer versions of Firefox you can change this shortcut in the Preferences Panel, accessible on the Add-ons page: click on the "Startup Key Sequence" textbox and type your new desired shortcut. If your version isn't new enough, you shouldn't see that textbox.
Please be sure to tell your friends that Tabhunter is now available in that other browser that anagrams to "ochre logo gem". Whatever, it still quickly helps you unearth that tab you know you brought up a week ago and haven't yet closed.
The one real new feature lets you select only tabs that are playing some audio. If you accidentally invoke "Reload All Tabs" and a bunch of tabs start playing music, you can now click on the "Audio Only" button and isolate them.
Also, Tabhunter finally supports changing the font size. See the prefs.
Apart from fetching favicons associated with tabs that are currently loaded in your browser, Tabhunter does not transmit any information to other computers. It saves some innocuous usage-related preference information in the browser's local preference cache, and if other users have access to it, either use a better password or speak to the person who set up your machine. If you're unsure about this, find yourself another tab picker.
[*] I'm sure this is coincidental.