If you want to keep your money from falling into the sticky hands of a thief while traveling, the best bet is to keep your cash where it can't be grabbed. For 16 years I've been using some kind of money belt from Eagle Creek to do that and so far the most I've ever lost to a pickpocket is 80 rupees. (A shade over $2.)
This isn't what you want to be digging in and out of while you're shopping in the market. Instead think of it as the place where you keep your back-up cash you don't need to have handy. I've walked around for weeks with $500 in one of these belts and nobody has been the wiser. You wouldn't know that there's a secret pocket on the back unless you saw the other side of the belt when it's not being worn.
The All Terrain Belt is naturally a double-duty item: it's a real belt after all. It holds your pants or shorts up as well as any other and this particular one dispenses with belt loops so it'll keep fitting well while you shed pounds backpacking around the world. One more bonus: there's no metal on it except the zipper. You can usually go through airport security without taking it off.
The Eagle Creek All Terrain Money belt is available for $15 at Magellan's, REI.com, and at EagleCreek.com.
If you travel more on business, you can also get a nicer looking leather one from $15 to $25 at BeltOutlet.com: Leather Money Belt by Austin House