Your plugin is the perfect place to fix web pages which try to use wingdings/webdings which are displayed in IE, but are no longer supported in any way by firefox (even the old hack which used to fix this no longer works in Firefox 3+). I hope you will consider adding this fix to your plugin. Search google for "firefox wingdings" for lots of forum threads by people frustrated by this. Many of those threads could be updated to link to your plugin once you have this feature.
I commonly run into this problem in Gmail when someone uses outlook to send an emoticon in their message. Outlook converts the smiley into a wingding, which shows up in Gmail as "J" in Firefox, but renders "correctly" in IE which is less strict about standards compliance.
Thanks for considering my feature request!
