Jonathan Miles Fingerjig Typing Game is the best thing in the world if you are looking to improve not only your typing, but also you vocabulary. It is also the signal most evil thing in the world. Because if you are confidant about your typing you will be crushed by this game.
Basically it pulls words out from it's massive library and has you type them. they start out short like mot and ennobling. then they test you on one side of the keyboard then the other. But then they whip out words like Prenominations, overdecorates, and epigrammatizers. And when your racing the timer, it's just not very nice.
Fortunately at the end of every section they show you what words you typed and if you click on a word it will send you to it's definition. Very handy.
I introduced this to my mom one day while practicing my typing. She got upset because I kept shushing her and told me it couldn't be that hard. My evil smile at the time should have tipped her off that she was in for a world of hurt. :3 I got such an evil glare from her when I pointed out that she was shushing me while she typed. :3
Since I started playing this game, barley once a week, I have noticed an improvement in my typing and it's speed. Seeing as how every job I look at says the want a minimum typing speed of 40-60wpm and mine is a lowly 28wpm.(up from 24) I have some hope.