Here is a picture of my hydraulic cart after it pulled an old
fencepost out of the ground.  (I first loosened the soil with
a shovel and cracked off a fair portion of the footing using
a chipping hammer.)  I built it because I was tired of lifting
rotten fence footings out of the ground.

The first test was to pull an overgrown plant out of the 
ground.  That required some root chopping, but neither
task required any 'dead lifting' on my part.
That made me very happy.

Yesterday, I used the cart to move a loaded workbench
out of the way so I could  repair some sheetrock.

You can see that the cart is a modified
version of:
http://tinyurl.com/cthjuj
or
http://www.northerntool.com/webapp/wcs/stores/servlet/product_6970_200365531_200365531

I replaced the manual hydraulic ram with a bottle jack powered
via an old windshield wiper motor.  

The cart lifts a 290 lb weight 22.5" in the air in 25 seconds just by
connecting the battery to the motor.
This is a 4x improvement in performance of the first version.
(I lightened the connecting rod and added an oillite journal bearing).

Here is a short movie showing the mechanism lifting the table:
http://mysite.verizon.net/reswoead/id4.html 

I removed the 5" solid wheels and welded on supports for wide,
soft 10" pneumatic wheels.  It now scoots over rough ground
with no problem.

Next, I am pondering brakes to make it easier to control on
inclines since the thing weighs about 200 lbs!

--Winston