I'm surprised this hasn't come out sooner: Google Goggles is a visual search app for Android phones that scans products, books, movies, business cards, bar codes, artworks—a ton of stuff. It's like Google robot eyes in your phone.
While it's not pixel perfect in its judgment, what's impressive is its depth—unlike apps like ShopSavvy or SnapTell, Goggles aims to search everything, even if it admittedly isn't great at IDing food or pets or cars. Yet. Plus, it's got integrated augmented reality powers, so it'll show you nearby businesses without you having to touch anything.
Considering Google's rollout of QR codes to a bunch of places, clearly, they're planning to splash big with visual search before some upstarts get the ball rolling—I figure it's only a (short) matter of time before we see it on other smartphones besides Android 1.6. [Google]