I have a Kinesys belt with a pouch that holds the camera + lens, plus an additional lens pouch. It's actually quite comfortable to walk around with, since all the weight is on my hips, but of course then the camera is put away so I wind up wearing it around the neck strap anyway. Plus Mr. Gfunk refuses to allow me to wear it around because he says I look like an idiot.
I really like the idea of the sling strap - that's actually how I often try to use my neck strap, with limited success since it's too small. I think I'll try one.