is a crazy tool that lets you find people across major social networks just by uploading a photo. I tried it and the results were scary accurate.
Understanding the mechanics helps you use the tool more effectively. When you upload a photo or paste an image URL into the Search4Faces link interface, the following happens:
A database for recognizing celebrities, athletes, and politicians based on data from Wikipedia and IMDb . How to Use the Search4Faces Link
A smaller but specialized database of profile photos from the audio-based social app.