There's a certain point where simply composing papers, lists, or writing things improves typing more than anything else.
FWIW, I typed 120+ wpm with 99% accuracy the last test I took, and it's not through drill -- it's through active and constant use of typing as a mode of communication.
(Also, my technique is bad. According to someone who watched me, I don't use the correct fingers for the keys. But at this point, I really don't think it matters. :P)