I like the idea, but the problem is that many of these marks are simply too obscure to be useful, some of them are copyrighted, and most importantly, only few of them have actually been allocated Unicode points:
INTERROBANG ‽ ‽
ASTERISM ⁂ ⁂
ARABIC QUESTION MARK ؟ ؟
REVERSED QUESTION MARK ⸮ &x2e2e;
AFAIK, only Kindles support these marks out of the box; you'd probably have to embed a font to use them in your ebooks.
Last edited by Doitsu; 10-08-2012 at 04:56 PM.