My Carradice Long Flap Camper Saddlebag. I can carry two gallons of milk inside the main compartment, and more smaller items. There are two large outside pockets, each large enough to hold a one-quart bottle of juice, or I can stuff carrots, celery, several small cans, or other small fruits .....

My awesome Timbuk2 Custom Commute Laptop Messenger Bag. Definitely water proof (tested in heavy rain and heavy splashes from traffic, where I got soaked, but everything in my bag was completely dry).