I have something similar to this:
http://www.penncamera.com/spec_sheet.html?catalog[name]=Lowepro-SlingShot-100-AW-(Black)&catalog[product_guids][0]=56797672-b5c4-4503-a2fb-b32902752075
it slings over your back - looks like a backpack, but you can swing it forward to get at the camera without having the remove the bag. It isn't beautiful, but it's little (fits a D80 with a lens, plus an extra lens, a small point and shoot camera, memory cards, etc.) and not bulky. I honestly just got my bag, so I can't say for sure about how long lasting it is, but it seems to be good quality, and I LOVE that it's easier to carry than a shoulder bag. I'm planning to take my camera hiking, etc, so a backpack/sling type bag was a necessity, as opposed to a bag. Plus, it's great to be able to access the camera, without having to handle the bag as well.
-GoingNowhere