The Dasher input method (aimed at people with disabilities who are able to enter data only by manipulating a pointer) uses a visualized trie with vertex areas p

The Dasher input method (aimed at people with disabilities who are able to enter data only by manipulating a pointer) uses a visualized trie with vertex areas proportional to linguistic probability: http://www.inference.phy.cam.ac.uk/dasher/DasherSummary2.html http://www.inference.phy.cam.ac.uk/dasher/DasherSummary2.htm... (Prof. Mackay, its author, uses it to teach information theory and compression, among other things.)