There have been a couple times that someone has posted a picture of their audio gear/home theater room and a few minutes later I posted an exterior photo of their house in the same thread.
They couldn't figure out how I knew where they lived so fast. Here is how I did it on one occasion:
1. Googled user name and found another forum that they posted in
2. Looked for classified ads in that forum and found picture of motorcycle for sale in front of house with house number showing
3. Looked up house number in county assessor's website (there were only a few houses with the same number)
4. Viewed attached photo at assessor's website to find match.
5. Copied and pasted photo or else used google maps street view to find house and cut/paste