For me, I found, the bast way to travel and move around town is as light as possible. For that reason, I mostly avoid taking any kind of bag, and only carry things in my pockets.
Right now that would be:
- HTC Desire (due to be replaced this autumn).
- House key (only one, no pendants or anything).
- Car key and remote for the garage, when with car.
- ID, drivers licence, bank card, public transport and library card, and cash, bound together with a rubber band.
- Spyderco Chaparral pocket knife
I take a Camelbak backpack when going away, or in the mountains, and also when going to the library. That's also due to be replaced, probably by the above mentioned GORUCK Echo, especially now that they came out with the sand livery.