We've got the BlackRapid SnapR 20. It's a snug fit with the lug in the tripod screw. It's not attached to the shoulder strap, it's just a wrist strap.
http://www.blackrapid.com/products/snapr-20

My dad was looking for a semi-rigid case and I found these for him.

http://www.ruggard.com/detail?sku=756000

http://www.amazon.com/Canon-PSC5100-.../dp/B001GN7A8A

In reality, it's either tucked away in my Crumpler 7 Million along with the SLRs. Or, I put it in my jacket pocket. Or, I just carry it in my hand. Or, I toss it in my wife's (large) purse.