I'd like to bump the first part of this question - as a newbie I managed to create several 'odd' projects that have since been deleted . . . but still appear in the Project Switcher list. I've poked around the files but can't find where this list is generated from to edit it (if that is even possible).
OK . . . as usually posting focuses the mind. I found the answer for myself before I clicked submit.
Close Sublime Text 2; open the file . . ./Settings/Session.sublime_session in an different text editor and look for the block workspaces : recent workspaces (at the end of the file in my case) and delete the unwanted lines. Save and re-open Sublime Text 2 and the 'ghosts' are gone from the Project Switcher.