Look up HTML5, CSS3, etc features, know if they are ready for use, and if so find out how you should use them – with polyfills, fallbacks or as they are.
HTML5 Extension for Windows Media Player Firefox Plug-in
Guacamole is an HTML5 + JavaScript (AJAX) viewer for VNC, which makes use of a server-side proxy written in Java.
an unusual paint program in javascript and html5.