Continuing on the theme of my last post, here are libusb-win32 drivers for the Atmel AVRISP mkII. Unlike the Atmel-supplied drivers, these support avrdude, and as a bonus they will install on the 64-bit version of Windows 7 without digital signature errors. Yes!
Note that if you want to use the AVRISP mkII with AVR Studio, these are not the drivers you are looking for. You want the ones Atmel provides (if you installed the libusb drivers by mistake, re-run the AVR Studio installer to revert back).