I am a graduate student in a math-heavy field, so I thought you might be interested in some feedback. Just yesterday, I was embedding LaTex-derived images into an HTML email in order to collaborate, and I thought: this is just so stupid. Your service definitely fills a need in the research community. I love it. What is the envisioned freemium model? A problem I can see is that very few users would need more than the service you are already offering.