This one looks nice. Might be bigger than you want, it's water proof.
http://www.amazon.com/Canon-Deluxe-B...amera+backpack
I use a backpack for my gear when we travel, or at weddings.
this one is smaller, doesn't say it's waterproof though.
http://www.amazon.com/Zeikos-ZE-BP2-...amera+backpack
This looks perfect
http://www.amazon.com/Case-Logic-SLR...amera+backpack