FrogPad Inc. has announced its one-handed USB keyboard with applications in
tablet PCs, hand-held, and mobile devices. The letter layout is based on the
percentage use of each letter in the English language. The 15 letters that
are used 86% of the time by typists are placed in the most efficient
locations on the keyboard. It was also designed using the natural drumming
motion of the hand. 

http://www.frogpad.com/
http://www.infosync.no/news/2002/n/2688.html
http://store.yahoo.com/eca/frogerkey.html