This bag makes me very happy. It's one of a handful of things that I'd take with me if I was sentenced to life on a desert island. It's so waterproof that I'd probably store rain-water in it when I wasn't using it to tote coconuts around with my dutch bike (one of the other things I'd pack out to that desert island). 

The Ortlieb Shopper is waterproof, and has a handy ziplock-style closing system. It's really just a big cavernous sac with a medium sized pocket and a zip pocket to keep keys and wallet easily locatable. I do my grocery shopping with it and if any bits of broccoli or berries spill down into the bottom I just slosh some water around inside and wipe it down. SO EASY. The shoulder straps are adjustable and I can carry it cross body if I have to, though usually I just sling it over my shoulder like a super-rad beach tote. I think it looks great in a sporty sort of way - it's tech-y but not too tech-y. Another thing that I love about it is that I can use it on both my bikes, which have very different racks. The sneaky-smart QL2 mounting system means that adjusting where it sits on my rear rack can be done on the fly. Not only that but if you have a rack with narrow tubing, the bags come with shims that fit into the rack clips so that it doesn't rattle while you ride. 

One last thing, these made-in-Germany bags have a 5 year warranty against any manufacturer's defects. Although defective products are few and far between, it's nice to know they've got my back.