[JRios1968]

If you run Firefox, you can get an extension called Xinha Here! that'll give you an HTML editor for the reply box. After installing it, you just right click in the reply box and select it in the menu.

I just downloaded it...very cool!
 

[JoJo Gunn]

It is pretty slick, huh?

It doesn't work on sites that use [ ] brackets instead of these:  < and >  And it's sometimes a little irritating (if you're in a hurry) because you can't just copy and paste several paragraphs into it unless you copy from source code first.

For sites that use brackets, there's this extension. (I have it, yet admittedly have very rarely used it because most sites like that which I frequent has some sort of editor at the reply stage. It's small, though, and causes no conflicts with anything else).