Formulax is a small Web application which renders formulae written in LaTeX on the fly and while they are being typed. It was designed to chat about mathematics and physics on IRC, ICQ, MSN, et al. where messenger plugins are not available. A formula author can pass a URL to dialogue partners to show them equations and formulae while they are being typed. Formulax relies on PHP, prototype (included), and mimeTeX (has to be installed). All that is needed on the client side is any JavaScript-enabled Web browser.