Nice. Maybe you should make the graphic a little bigger? On my screen it got kinda lost.

And of course you'll need to add the Curl mods! Nah, just kidding, you're fine. ;-)

If I may venture another opinion: The white text on yellow didn't work for me – either the contrast will be too low or the yellow to "dirty". How about using a blue or something instead? Symbolically, yellow is more of a warning color anyway while blue may be used to symbolize information or something non-critical. A gray might also be used but that's boring.

Or just use Ctrl(+Shift)+F5 for a hard page refresh.

I wonder why my WPM on your page is around half that of other tests (35–40 vs 70–80 elsewhere)? Do you use the convention of 5 strokes per word including spaces? If not, you really should. If you report much lower WPM than people are used to, they'll get sad and eventually leave the page for a more encouraging one. ;-)

It's a bit stressful to only see the word you're typing – in other games/tests you can often see what's coming. Would it be an idea to put buttons next to the green one on each side, the left showing the last word and the right one showing the next word? The previous/next word buttons should be toned down – maybe a light (or grayer?) green background and the words grayed out to reduce contrast.

WPM is computed off 5 chars not including spaces = 1 word, over the last 30 seconds; I can fix that. However, I think the lower WPM is mostly a result of the fact you can't see the next word until you finish the current one. I'll put the ability to see the next word(s) on my to-do list, alongside a check to prevent the same word from being randomly selected twice in a row.

Exactly. Actually, it is based off of http://learn.dvorak.nl/ (which I found very effective for learning Dvorak) but has the advantages of only using words that contain the current stage's new letters, dynamic WPM counter, and a much-improved wordlist.