Google is your friend:
http://mkweb.bcgsc.ca/carpalx/?tnwclr

The vowel placements on that one is just delightful.

Now let's see if SpeedMorph or someone else here can make a worse one!

I reversed everything so that whenever something bad happens, instead of adding to the score, it subtracts. So it still tries to get the lowest score possible, but lower scores are worse, not better. So it was as simple as switching a number, I just had to find the right thing to switch.

My Bad Keyboard

      12% 10%  4% 36%         14%  3%  2% 14%

       l   c   m   r   n   o   b   p   k   h 
       ;   ,   x   v   d   .   q   '   j   z 
       a   s   g   i   e   u   f   y   w   t

Total keys pressed: 13362031

Overall Score: 101.6
Distance: 29875563 meters
Same finger: 13.32%
Same hand: 31.5%
Same hand reverse direction: 2.98%
Jumping over the home row: 14.14%

Reversing direction on 1 hand: 2.98%
Changing rows: 4.72%
Reaching to center column: 10.87%
Inward rolls: 5.04%
Outward rolls: 1.31%

******
Compared to QWERTY

Overall Score: 50.3239174493758
Distance: 23205684 meters
Same finger: 3.24%
Same hand: 24.61%
Same hand reverse direction: 2.76%
Jumping over the home row: 2.94%

Reversing direction on 1 hand: 2.76%
Changing rows: 10.34%
Reaching to center column: 5.23%
Inward rolls: 4.12%
Outward rolls: 3.74%

******
Compared to Colemak

Overall Score: 16.4924114455355
Distance: 9357811 meters
Same finger: 0.6%
Same hand: 22.0%
Same hand reverse direction: 2.1%
Jumping over the home row: 0.28%

Reversing direction on 1 hand: 2.1%
Changing rows: 8.64%
Reaching to center column: 2.02%
Inward rolls: 3.83%
Outward rolls: 3.39%

You can also systematically create a very bad keyboard. This can be better, because there are certain issues that only occur when they're heavily pronounced, so my program ignores them.

Start with the worst position on the weaker hand on the weakest finger. Place E there. Then move more common keys on to that finger and hand, starting with the weakest keys and avoiding the home row. Pile as much weight on as few fingers as possible.

Example:

r l b y n d , c f h
p ' ; x k . z q j w
e s m i a v u g o t

I made that by placing R and E on the pinky, which is not only stressful, but causes same finger. Then I put T and H on the other hand, which is also stressful and causes same finger. Then I put O and F on one finger, with O in a hard-to-reach position.

Then I put N, I, and A on one finger because of the very common IN and AN digraphs.

For the rest, I was basically just placing by letter frequency. This gives you a very frustrating layout which will murder your pinkies.

I have LAS and SAL, but that's about it. Sorry to disappoint you. :(

Nice one. You should also encourage alternative fingering: The middle finger on each hand should rest over the bumps, so the pinkies get a little more exercise. The lazy buggers need to get a real workout if they are to be whipped into shape.

Then try typing 'themes' 100 times.  ;)

Crazy idea: Maybe layouts like that one could be used for training your weak fingers? I know that Daniel Chen recommended active motor training of the weak fingers. But people would probably not care much for the hassle of using another layout.

Heh!  I hadn't even thought of that.  The evil twin was even eviller than I thought!  :)