Simple in browser editor with syntax highlighting

I've been looking at highlighting various bits of text in a text are as they are being edited. I've had a play with code mirror, whilst its seriously impressive its just too hard create another mode for it.

Ideally I'd be able to indicate what I want to highlight with a regular expression. Or something equally simple.

as an example I'd like to highlight @username twitter style and #tag as well. There are cases where a line starts with.

property:: value

that would be nice to emphasise too.

A simple way of creating开发者_StackOverflow a really dumb parser for code mirror would be very cool, that way the advanced option is there for someone with more JS talent than me.

I've got a horrible feeling that this is something that is just hard to do though.

All suggestions welcome.