Wait what? Have you been to any IRC channel in the last ten years?

IRC is a well-supported, still widely used, open standard for real-time communication. It can work just as fine on the browser with any of the hundreds of browser-based IRC clients. Heck, you could probably hook this Jabbr front-end to an IRC server without much pain.

Jabbr looks nice, but it's just a cute IRC reimplementation.