Guacamole is a very promising-looking HTML 5 VNC program. The latest stable release is 0.2.6, and is only available in source code. If you don’t mind getting your hands a little dirty, dig in. It has quite an impressive list of features.
- Near-native performance
- CopyRect encoding (if supported by VNC server)
- Client-side cursor (if supported by VNC server)
- Java servlet server-side proxy (requires a servlet container like Apache Tomcat)
- Mouse scroll wheel support
- Clipboard support
- International keyboard support