Just took a look at a Ritchie Pro stem I have on one of my road bikes: 5Nm (~45 in-lbs) stamped on the side of the stem; same for the bar clamps.
Profile Design H2O: 6.77 Nm (60 in-lbs) as specified in the destructions.
Nashbar various stems: 85 in-lbs (9.5 Nm) (specified in instr.)
Hope this helps -
- Wil