Android (f/w 2.1+) on screen keyboard for multiple languages
Learn touch typing without leaving the terminal
A Vietnamese keyboard for Windows and Linux
Unicode On-Screen Keyboard: insert text snippets into any Windows app
A simple tool for typing characters in different writing systems.
Keyboard layouts that provide a Linux-style compose key on OS X
The Marathi Virtual Keyboard is the Plugin for web application.
Onscreen keyboard for eye tracking systems