There have been several previous hints regarding keybindings. This one will explain how you can activate the BBEdit-like 'twiddle' command, which transposes two adjacent characters. Since 'transpose' is an action which may be bound to keystrokes, it is possible to add the following line to your user's Library -> KeyBindings -> DefaultKeyBinding.dict file and get the twiddle feature in Cocoa applications:
"^`" = ("moveBackward:", "transpose:"); /* bbedit twiddle */
Since transpose acts on the characters to the left and right of the cursor, the moveBackward command allows one to place the cursor to the right of the characters to be transposed. Pressing Control-` will then transpose them and leave the cursor in its initial position (transpose moves the cursor forward).
Mac OS X Hints
http://hints.macworld.com/article.php?story=20041026211641708