I'm usually carrying a 5D, although I don't haul all the gear with it I would on a paid shoot. I can tuck it with a 50mm lens and a 430ex flash in a very small bag. For a beater I use my old 20D, but I'm rarely in a situation where I'm worried about the camera.
I recently bought a Canon G7 because I wanted a very small, pocket-able camera, but I find myself disappointed with it's quality faster than ISO 200. I like it if I know I'm only going to be outside in the daytime. I tried sticking with film for my compact point-n-shoot for a while, but dealing with film processing just annoys me anymore.
When I can get a digital compact with an 8mp APS-C sensor I'll probably stop hauling the DSLRs everywhere. I can't believe I'm still waiting for Canon or Nikon to bring me that camera. I had high hopes for the Sigma DP1, but I don't think it cuts it for the price. I just want something that can match a 20D for basic image quality.