Further tangent: a colleague and I talked about creating a derivative of one of the programmer fonts, replacing smart/curly quotes and another such nuisances with unmistakeable indicators.
This would be a useful feature for any programming font. I can totally imagine writing exploits through zero-width characters; smart insertion into interpreted strings (scanners/parsers) can potentially insert a security leak by an attacker. Though input can come from many places off course, this would at least make one vector visible.
You could probably just invert any non-ASCII character, and you could probably do this programmatically over an existing font.