Ditto on Black Rapid. I use a Nikon AH-4 Hand Strap and even though it offsets the tripod mount hole, I have never had a problem. I carry a 5D and a 40D (with or without grips) in the same manner using various Black Rapid straps while outdoors, hiking, camping, etc. Using the D ring type R-1 fasteners, I also use a carabiner sometimes to hold the camera to another carabiner on my leather belt. This is good for when I don't want the whole strap on but need to have my hands free. Using two carabiners isn't as fast to bring the camera up, it requires requires two hands to disconnect, but it works great when I know I won't be shooting all the time and don't want to lay my camera down somewhere. If I do use a neck strap around my shoulder or something, I have always liked Op/Tech for many of their products.
There are also a few alternatives to Black Rapid - Sun Sniper, Carry Speed and Camera Slinger.
Word to the wise - try to never lay your camera down outdoors, around food, drinks, boy scouts, etc. If I need to put it somewhere, I keep my camera bag and day pack carabinered to a tree with a heavy duty bungee or something so it is completely out of the way. (In a trustworthy safe area of course.)