Google Images now lets you search by image instead of keywords. You can give it an image and it returns images that look similar, at least to its algorithms. I immediately put it to the test by giving it my mugshot from Stack Overflow. Hmm. Mostly women, with a few babies thrown in. It seems to be having more luck noticing that I'm wearing a black shirt than that I'm male.
Maybe it's because the photo I gave it has the top of my head cropped off? I try the mugshot from this blog. This time it successfully finds web articles containing that same photo, and also comes up with a few faces that do look vaguely like me. Not sure what Angelina Jolie's doing in there though.
Okay, clearly these are early days for this technology, but I applaud what they're trying to do. I look forward to the day when it's so reliable that it can spot family resemblances. That would make a useful complement to the Relative Finder in 23andMe. Another search engine I would like to see is one that let's you hum a few notes of a song and then tells you what it is. Targeted ads could include places to buy the song, or Singing Lessons if it thinks you're off tune.