People carrying backpacks are prime targets for pickpockets. It's easy enough to unzip a compartment and take what's inside without alerting the dude carrying the pack. That's why it's usually a bad idea to keep valuable and important items in exterior pouches; however, stuffing them deep in the main compartment usually makes retrieving them difficult -- not ideal for stuff like passports, credit cards, smartphones and cash. The Defender Anti-Theft Backpack offers a compromise.
While the name evokes images of a futuristic smart bag that electrocutes people who aren't authorized to access the bag, that's not quite what it does. Instead, it simply uses closures that make it difficult to open any of the compartments discreetly, so you'll quickly be alerted when anyone attempts to sneakily pick any of your stuff.
The Defender Anti-Theft Backpack uses a main compartment with a difficult-to-access zipper configuration, which is hidden on the rear, facing towards your back. As such, even the sneakiest pickpocket will have to come in contact with your body if they attempt to unfasten it. For stuff you'd like easy access to, there are exterior pockets on the sides and backs, all secured by noisy Velcro straps that's guaranteed to make a ruckus when opened; there's also a zip pouch on the shoulder strap where you can keep your phone for quick retrieval.
Bag construction is cordura and rip stop nylon. It measures 12.6 x 18.1 x 4.7 inches (w x h x d), with a padded main compartment large enough to hold most any size of laptop, along with other gear.
Currently, the Defender Anti-Theft Backpack is undergoing crowdsourced development at Quirky. Present projected price is $24.