I have one of these stoves:

http://foldingfirebox.com/

I love it. You can set it up for an alcohol burner, sterno, Esbit, Hexamine, woodburning, etc. It's probably too much stove for just a stow-away-in-the-office emergency setup, but it's a really nice stove IMHO. If you're using something other than wood burning (alcohol, sterno, etc) it's a really good windscreen and pot support.