I just picked up an Op/Tech strap for my new K20D to relieve some of the weight (esp with the battery pack attached). I realized I can kill two birds with one stone with the Op/Tech, having both a shoulder strap and a wrist strap. I tend to prefer to wrap a camera's strap around my wrist when doing street and travel photography, I find it faster to use, less cumbersome, and more secure. But full-length should straps are rather too long and bulky to be turned into wrist straps unless skinny, but skinny straps are less tiring on the shoulder after a while with a heavier camera. The Op/Tech Super Classic strap that I bought offers a neat solution to this that doesn't require buying a separate wrist strap (which Op/Tech also sells) Thought I'd share how.
Here's the Op/Tech Classic attached to the camera. It's a long strap, so the camera hangs down almost at my hips (I'm 5'10"), which I prefer. I hate having a camera at armpit/chest level.
Here's a close-up of the strap - it has little rubber nubbies (that's a technical term) embedded into the neoprene, so it is very non-slip (compared to the Domke straps I've used for years). The stretchy neoprene absorbs shock and keeps it comfy.
The trick with many of the Op/Tech straps is that they are conceived as a system, and you can swap pieces in and out. So the middle pad piece comes off with the plastic snaps. This leaves two dangling pieces of webbing...which can be snapped together to form a small strap.
Wrap this around your wrist and off you go!
A couple of notes: The Super Classic strap comes in two versions, regular and "Pro-Loop". The Pro-Loop has a slightly different way of attaching to the bracket on the camera but more importantly the webbing pieces are much shorter. This made it too short to use as a wrist strap. Second, to get the webbing long enough to use as a wrist strap it does make the combined length of the strap when worn over the shoulder quite long, so if you prefer carrying your camera on a short strap this possibly won't work for you.
But I'm happy I don't have to buy/carry/swap a secondary wrist strap!
Super Classic page