Seems to work fine here basically, though I'm not using any controllers.
Windows 7, 64bit.
Cool, first reported test with windows 7

, were you using a 64bit browser and 64bit JRE?
It picks up my HP Quick Launch buttons but it only shows them all off and no changes when I press the buttons.
Hmm, no idea whats going on there, I've seen similar things under linux, but not windows before. I'm guessing it's extended button codes or something, I really ought to write some extra debugging utilities ... at some point

.
Not sure if this is a bug:
Caps lock/scroll lock picks up being pressed but then show off when there still on.
Nope, it's the caps/scroll lock key, rather than the function that it's measuring, so unless you hold the key down, it should return to the unpressed state, even if the caps/scroll lock is still on.
Thanks for testing it
Endolf