I bought a 'Bone' creeper a couple weeks ago.
http://www.bonecreeper.com/bone.php3

It's a great product and a dream to use.
I recommend it highly.

I noticed that it shared a design issue with other brands of
creeper, though. If I was oriented a few degrees more or 
less than 'normal' in relation to the street, it would try
to steer me headfirst down my driveway ramp and into the
sidewalk.

This was way more excitement than I wanted, so I
replaced the pivoting casters on the 'head' end of the
creeper with non-pivoting type. I used a 1/2" button
head screw to attach each caster and a smaller screw to
hold wheel alignment after adjustment.

http://www.metalworking.com/dropbox/BoringBone1.JPG
http://www.metalworking.com/dropbox/BoringBone2.JPG
http://www.metalworking.com/dropbox/BoringBone3.JPG

It is now much safer to use on the ramp.  I can now
easily maneuver and hold at any angle from -90 to +90
degrees in relation to 'street normal'.


--Winston