Google and other search engines are quite handy for all kind of background checks. Newsgroup postings, old home pages etc of individuals can be found easily. For companies the internet presence is not just their own site but everything coming up after searching with their name. Adding 'problems', 'bad service' or 'horrible' after company name and searching with that might bring up good amount of ranting from unhappy customers.

But there are also more interesting cases from companies. Some time ago I was looking for a job and checking company background info for my interview. By accident I found complete source code for one of their products. It was exposed due some mistakes with WebDAV setup and robots file. At least I had much better idea what that company was doing.

Today I just read from one user group mailing that O2's mms2legacy service is cached by Google. Searching with inurl:mms2legacy seems to bring a lot of pages MMS messages with photos and phone numbers. I could imagine that senders of those messages did not intend them to be available like that. Maybe O2 should add a disclaimer that they take no responsibility whatsoever of the visibility of the content.

Edit: O2 pulled the plug fast, so fast that they left navigation menu items leading to 404 pages.