I really like Stackshare’s listing of technology stacks used by various companies from big to small, many of which we’ve heard of.
It’s not so much useful to take a large company’s usage of a technology as an endorsement. Amazon, for example, wrote their original web technology in PHP, and still has significant chunks left. According to an insider, PHP is “banned” for new functionality on the grounds that PHP can’t be adequately secured.
It is useful to see where new technologies have been adopted, and get some context on how other companies are evolving their technology. After all, there is something of a network effect for any technology or product: more users means more developers and support which means more users, etc.