Is this the bike?(from your RAGBRAI photos--nice journal.)
The stem looks like it has quite a bit of rise already, so a stem like a 25 degree or 40 degree wouldn't help much.
40 degree angle stem:
This is a stem extender
. It clamps in place of your stem and has it's own top plate (and longer central bolt, I assume).
Your bike has a threadless stem. The fork's steerer tube extends up from the fork and the stem clamps onto it with the two bolts. The top bolt and cover are used to set how tight the stem pushes down against the bearings before the two bolts are tightened. EDIT--what norwood said--it's not hard, but you need to know how it all works together.
I don't know much about bike fitting. But your bars appear to be about level with the saddle. If you raise them a lot, you would put more weight on the seat, and less on your arms. Would that be better? I don't know.
Last edited by rm -rf; 10-15-09 at 08:12 PM.