Just wanted to get it out there since I couldn't find it mentioned anywhere here.
If you know you have good power feeding your Pi and your usb keyboard is still throwing random extra repeats or generally uncontrollable. I happened upon a repeatable solution.
1. Make sure you have ssh running already and you know your ip address and login creds.
2. ssh to your pi and login as root or sudo bash to get root
3. dmesg | grep usb
4. Find your keyboard device id listed above. it will be similar to the form below..
5. echo -n "1-1.2.3" > /sys/bus/usb/drivers/usb/unbind
6. echo -n "1-1.2.3" > /sys/bus/usb/drivers/usb/bind
7. Try typing on the keyboard and more than likely if it's not a power issue you no more repeats until next boot.
I happened upon this while reading a different forum post about how they got their keyboard to work by unplugging then plugging back in. That SOMETIMES refused to bind for me actually, but this method has worked for me 100% so far.
One step closer to closing the usb stack bugs.