Day one I put a Camdapter Arca plate and Canon E-1 hand strap on my 40D. It will come off the day the camera dies or I sell it. It's invaluable to me.
I also have the standard cleaning tools (blower, brush, pec pads) and a second battery, but that's it as far as accessories go. I'm not a fan of battery grips, cause they're heavy and they limit the camera bags I can use.
