I made a more clever "Transpose Chars" and "Transpose Words" that I used to use there in Alpha and have passed now to TextMate. The behaviour is:
Exchange the last (before cursor) chars. But attention: it exchange the last real chars, ignoring spaces around. This is the desired behaviour for the typical mistake everybody does. It is for me annoying to need to go back, put the cursor in the middle of the swapped chars and press ^T.. How many keystrokes?
"Exchange words" do the same thing, always ignoring the spaces.
If you have several selected words, "Exchange words" interchanges the first with the last word, leaving the rest untouched. Same thing with "Exchange chars"
I hope this is what you are looking for.
Binded to ^T and ^-Opt-T and no special scope.

----- Juan jfalgueras@uma.es