Most programming languages use backslash as a delimiter delimiter. Maybe this would work for MW as well?
The WikiCreole proposal is to use ~ (tilde) as an escape character:
http://www.wikicreole.org/wiki/Creole1.0#section-Creole1.0-EscapeCharacter
Unfortunately this conflicts with our signature shortcuts.
-- Tim Starling
Also a bad choose for escaping from URLs, as it's quite common. What about ¬ ?