I'm not much of a sling bag kinda guy, but here's a really great deal on one if you are. There's a nice discount today on the Lowepro Passport Messenger Shoulder Bag for Compact DSLRs or CSC Cameras. Typically floating around $40 dollars, today it's just $19.99. There's a cool little video over on the product page that explains how this bag works (click here).
Lowepro Passport Messenger Shoulder Bag for Compact DSLRs