No matter where we travel, stateside or otherwise, we seem to exude tourist nerdism--which means we're an easy mark for pickpockets and con artists. So even after resorting to dorky money belts and the like, we could still use all the help we can get.
That's why we're so grateful to Tokyomango for pointing out this counterfeit bill detector, which uses ultraviolet rays to scan paper currency for authentication. It was introduced in Japan for that country's universally known camera-toting tourists, but we see no reason the technology should be limited to any particular population. If it were combined with a GPS device that can keep taxi drivers from ripping us off, it would be the perfect travel companion.