I'll give it a start, my current set of tools for this objective would probably be: Light-weight PHP front-end (epiphany, minimal framework) for user authentic

I'll give it a start, my current set of tools for this objective would probably be: Light-weight PHP front-end (epiphany, minimal framework) for user authentication against MYSQL database that just holds user data and nothing else. CSS3 + HTML5 templates, dynamically rendered/finalised on-the-fly through AJAX calls and JSON data that gets filled into those templates through JavaScript. Hosted on a root or virtual server. Can be scaled by duplicating servers (possibly even EC2) and load-balancing if necessary. Though a good root server handles 100k users a day without a hitch. Alternatively: Javascript+HTML5+CSS3 hosted on S3 and authentication run through the API backend. Traffic-immune, deployable anywhere, easy to test. Minimal cost. Might feel odd to the user though, when everything just clicks/works instantly (look how far we've come).