I received a comment under one of the other posts where a reader who calls herself “Aunt Lee” noted that she has collected links to a number of on-line games. I tried these and many of them are pretty good. They have a variety of motivators. One of them involves a game where you keep a skateboarder on his board as long as you are keying accurately.
Check out Aunt Lee’s page at http://www.auntlee.com/typinglinks.htm