Even though I'm a very savvy traveler, skillful pickpockets -- they're pretty much all skillful if they want to survive on the streets -- managed to get into my backpack when I visited Madrid several years ago. Within seconds, while I was engaged in conversation with a stranger, the second member of what was a team took all my valuables: passport, driver's license, all my credit and bank cards, and my money (luckily there was only about 50 Euros). Since then, I altered the way I carry my gear but a number of theft-proof items are also now available.
Below are my reviews of two of these products: Adam Rapp of
http://clothingarts.com/ offered me a pair of his Pick-Pocket Proof Pants (the Adventure Traveler Pants model), and Alex Ivory, the founder of
Dovetail Travel in Peace, sent me a small zippered black pouch containing two of her body bands. While the latter is a women's product, the Adventure Traveler Pants are currently only available for men -- though Clothing Arts will soon be manufacturing women's pants. (My friend tested out the pants and provided detailed feedback while I also tried them on to check out the multitude of features.)
1. Clothing Arts - Pick-Pocket Proof Pants - Adventure Traveler Pants

Sure, these cargo-type pants are expensive at $110, but they're absolutely worth it. After all, if a pair of pants could positively protect you from theft of your passport, money, credit cards, cell phone and more, how much would you be willing to pay? My friend at first was shocked at the price. But he found these pants to be nicely tailored with a perfect fit. He noted the high quality production, whether the zippers, stain-resistant material, and thick, slash-resistant pockets. Though he doesn't travel anywhere near the amount I do, he admitted that he'd definitely wear these if pickpockets were a threat. Sometimes he has to do business in some not great neighborhoods here in New York City and these pants would come in handy. He'd put his most valuable items (such as a wallet) in one of the zippered pockets that are covered by buttoned flaps. (There are also flaps over the vertical zippered pockets.) The flaps on the rear pockets, he added, were so hard for him to unbutton that he thought it would definitely stymie a thief who, after fiddling with buttons would then have to also undo the zipper. (It took my friend 10 to 15 seconds to undo the buttons and the zipper on a pocket.) Plus, one pocket has a hidden -- so hidden that we both had difficulty finding it -- inner zippered pocket that fits your most valuable item: your passport. It's hard to imagine how a pickpocket would navigate inside that pocket. In my opinion, you'd have to be unconscious for a thief to get into these pants pockets.

These pants have so many pockets, including one that's attachable to hold a small water bottle, that you could skip carrying a tote bag. (The pants can easily accommodate a guidebook, small camera, cell phone, note book and more.) You don't even have to wear a belt since there is a buttoned waist cinch system.
My friend said he'd wear these pants if theft were an issue, which it is in many cities around the world. If you are placing valuables in the rear zippered and buttoned down pockets, choose items that you won't need to access frequently during the day. (It'll just take too long with the buttons.) He decided that around town here in New York City, he'll just forgo the double layer of security and use just the zippers. That's an option here, of course. But it's nice to know that so much thought went into the construction of these pants. I can't wait until the woman's version is available.
2. Dovetail Travel in Peace
I've been in plenty of situations, such as an overnight train to Sicily and the souks in Morocco, where I wished I could really hide valuables so no prying hands can get to them for the entire day or night. These two super slim body bands -- the Travel Band and the Travel Wing -- to the rescue. When I opened the petite zippered bag, I found two black items that resemble lingerie of sorts. Both items (and they can be worn separately over your underwear: the wing goes over your bra and the band slips over your panties and sits on your hips) are mostly black nylon with a little spandex. The idea is that the stretchy pocket in each band is supposed to accommodate a plastic portfolio where you can slip your passport, money and credit cards.

I found that the portfolio (stuffed with my passport and credit cards) was a snug but good fit in the Wing, which you wear with the pocket along your upper back. However, I just didn't like what appeared to be the plastic odor off-gassing from the portfolio so I dumped it in favor of simply placing my passport in the Wing. That worked out fine. Then I donned my
ExOfficio shirt and my
Horny Toad jacket or I wore the Wing under one of my
Icebreaker dresses, and I felt perfectly comfortable and secure. (The Wing has a very low profile so it was not visible under my clothing.)
I also tried out the Band which has a stretchable inner pocket that's also supposed to accommodate the portfolio with your passport and valuables. However, no matter how much I stretched and tugged, I couldn't get the portfolio or the passport by itself into the narrow pocket. The portfolio just is too wide to fit into this pocket. No worries, though, because I simply put my rolled up bills and credit cards in a small zip lock and easily folded it into the pocket of the Body Band, which you wear with the pocket towards the back of your hips. It was plenty comfortable with its one-size fits all, up to size 10 for both bands. (At this time, these only comes in black but other colors probably will be available down the road.)

Of course, both the Band and the Wing are meant to hold items that you won't have to access during the day. They're for close-to-the-body safe keeping. It's not like you're going to peel back your shirt to access your passport at customs, or lift up your skirt every time you need money to make a purchase.
I think Dovetail Travel in Peace is a great idea for female travelers who need to keep valuables secure no matter what. And, at the price of $48 for the set, it's definitely worth it.