ChordKey (demo) APK

ChordKey is an experimental chorded keyboard application for Android. It allows you to type one-handed using different combinations ("chords") of only five keys, similar to Doug Engelbart’s original chorded keyboard.

ChordKey uses the Microwriter alphabet, invented by Cy Endfield and used with the permission of Chris Rainey. For best results, we recommend using the CyKey hardware keyboard with a PC:
http://www.cykey.co.uk/

This application is designed to be used on Android tablets (phone screens are typically too small), and requires touch screen hardware that supports at least 5 simultaneous touches.

See here for a brief tutorial:
https://sites.google.com/site/cykeybellaire/cykey-home-page

For additional reference on the Microwriter and AgendA see:
http://en.wikipedia.org/wiki/Microwriter
http://research.microsoft.com/en-us/um/people/bibuxton/buxtoncollection/detail.aspx?id=5
http://www.computinghistory.org.uk/det/5794/Microwriter-MW4/
http://www.ericlindsay.com/palmtop/mwrite.htm