You might try a leather PDA case. That's what I use for my EDC kit here in Silicon Valley where a Leatherman on your belt will raise eyebrows but nobody even notices a PDA.

Check out:

http://www.pdaskins.com/products_dd.html

I have both the PDA Plus and the PDA Pro Phone. The PDA Plus has my EDC kit and the PDA Pro Phone has my toolkit. The phone pocket fits even a large multi tool.

They hold a fair amount and come with both a belt clip and detachable shoulder strap.