Allow users to switch which theme they use on your WordPress, WordPress MU, or BuddyPress site.
This plug in is installed on ScienceGuardian.com as a legacy from the colleague now unavailable who tweaked the WordPress theme I use to look like the blog's previous incarnation on another host used earlier.
The WordPress theme I use is New AIDS Review which is the adaptation referred to above, a tweaking of Michael Heilemann Version 1.6, which is "a default WordPress theme based on the famous Kubrick."
In updating WordPress to 3.5 I have left Theme Switcher switched on because inactivating it produces major glitches in the operation of the blog. Yet I have never used it - and don't believe any user even knows it's there. But for some reason it now forms an essential part of the blog needed to operate it properly. I don't dare switch it off or remove it!
Your mileage may vary. But if anyone know what is really happening and how to remove it safely, please advise.