When my partner (who is from the EU) got to the US this most recent time (she visits here for 90 days at a time, as allowed under VWP rules), immigration pulled her aside with a printout of (public-facing) facebook pages on their desk. Interesting only in that her face book is not under her official name. They had pages and pages of printouts that they thought proved she wasn't simple a tourist, and that she was working here, etc. Note, it was all public (or semi-public with a lot of crawling around under alternate emails, leading to other names, etc etc) so nothing "intercepted". But still a bit worrying when you get pulled aside and someone has a folder ready full of pictures of you, your business website (freelancer), your facebook posts, your tweets, etc