The BlackRapid RS-5 is by far the best dSLR camera strap I have ever seen. Barry Anderson of Mogo media and 5DMKII shooter introduced the RS-5 to me when I was DC for the Photoshop Live event. At the time, I was lugging around my beast of a camera all morning and had the worst neck spasm from shooting video footage of the White House (yet to be edited :S).
The BlackRapid RS-5 is not only comfortable, but it redistributes the weight of your camera so that you feel no stress on your neck. The locking fastener screws directly in to your tripod socket and allows you to quickly grab and swivel your camera. It makes you feel like a photo ninja. Hiyah!
Another great feature is the handy pocket in the strap which fits your iPhone, iPod or a Flip. There is also a zippered pocket where you can store extra batterys, memory cards, biz cards, and very small snacks!
Mine just arrived today! Photowalk anyone?