I just noticed that ebags.com has a category called "Man Bags" ... cool!

I used to carry a smallish Eagle Creek shoulder bag (I don't see it on their current web site) when I did daily train commuting ... and before laptops. I still use it when traveling to Europe. Its my on-plane bag. For commuting it was just big enough to carry what I needed. Most of what I'm seeing now is too purse-like or has flaps that are too big (flaps get in the way), or has buckles.

I have a very good idea of what I like and what I don't. For example, it needs a full flap on top - to be rainproof, but the flap shouldn't be too long, otherwise it flops into the way when you're trying to look into the bag. The top of any compartment needs a zipper - so contents can't come out when the bag is inadvertently inverted. It needs a few different compartments - to organize the smaller items, but still have a main compartment large enough for small books ... I'm thinking about the size of an 8-1/2x11 sheet of paper folded in half. Oh, and no buckles - they are just obnoxious.