Unconventional or Unheard of pairings?

[ralst]

For a moment forget about the pairings you see cropping up on here every week and turn your attention to those unconventional or unheard of pairings that you secretly feel exist only in the back reaches of your mind. What are the pairings you've never seen or seen once and have been searching for ever since?

Off the top of my head I can think of three:

Helen/Joy - Drop the Dead Donkey
Susan/Jenny - Teachers
Britta/Annie - Community

What are yours?