I always thought one of those square carry-on bags would make a great BOB/Emergency kit. Like this:

http://www.seatkase.com/


Their somewhat rigid design means one can use it for a quick improvised seat, they roll along the ground better than a typical wheeled duffel bag, they have a big opening that allows one to easily see everything that is in there and grab what they need quickly with minimal displacement of other items. The only other thing I would like is some shoulder straps so it could be carried on one's back if the need arose.

Otherwise, I would love to buy enough of them so that I would have one for each member of my family, then turn them into BOBs/emergency kits (something along the lines of the Ready.gov emergency kit recommendations).

I remember reading a topic that had a link to a company that sold large wheeled, all terrain camping bags. Yoy could even get a large T bar handle as an option.

Even computer challanged me has finally learned to use the search function. Checkout: www.sherpacart.com

Got this one in black for everyday train commuting.

The best part is that you can detach the backpack and use the wheeled cart to move something else. Also the vertical shaped design allows for much more tolerable maneuverability in public transport considering its volume. The handle on this model is much stronger than anything I saw in the larger travel wheelers. Rain cover is included too.

In urban environment it made 40 miles already (1 mile every day).

Here's another nice one, designed to be used as a trailer, pull-along luggage, or backpack. The bag has a 70L capacity, which is fairly large.

http://www.carryfreedom.com/city.html