What we really really really really need - well I do anyway - is a little devil face indicating an evil smile, for, like, when you suggest someone strikes their DH over the head with a frying pan but would never advocate domestic violence of course, or sewing prawns into the curtains, or giving a classic passive-aggressive reply to the MIL from Hell.
I manage by typing but it's just not the same. In an email I type it like this > : ) only without the spaces of course. (Without the spaces on here it would turn out as >:) and that would be silly.)
If you can do a 
(and don't we all love the ), a devil should be no trouble for you at all. I bet it would be ever so widely used on some forums - AIBU springs to mind. 
in anticipation.
Annie the