I like the tilde one because I've never seen it before.
----------------------------------------- It is much harder to be a liberal than a conservative. Why? Because it is easier to give someone the finger than it is to give them a helping hand. Mike Royko
that is. Though perhaps Ashton's old standby of :-þ is something to consider too. Maybe with a winky - ;-þ
I dunno. There will always be some ambiguity unless there's something like [image|/forums/images/warning.png|0|This is sarcasm...] attached to it. Perhaps the Sign can be replaced by: WSWS! if text is needed.
I think we need an RFC on this. Who's willing to start the process?