I'm afraid I was in danger of joining the ranks of Silkstone in the 'camera-bag-addiction' department! But I have tried keep a lid on this compulsion to buy bags galore
My main bags are now:
Lowepro Slingshot 200 - holds pretty much everything I have (bar tripod) and is comfortable/easy to use.
Crumpler Pretty Boy XL 4000 - as a multi-purpose bag and for mainly when I want to go walking with 'just' the body and the choice of the 70-300mm and a smaller lens.
Lowepro Mini TLZ - for when I just want the body/small lens.
I have others... but these are the ones that actually get used