Never happened in the US, but;
1) Le Meridien Vilnius comped Mrs. jb and I a nice dinner;
2) AF (ok, not *wood) gave us a nice bottle of Champagne;
3) Le Meridien Budapest gave me a nice Hungarian souvenir
4) Sheraton Saigon comped Mrs. jb and I a magnificent dinner.

I have been surprised and pleased at these things.There have been a few over the years from others too, usually with some other business involved, but these were all things that happened just because somebody noticed the dates and took the action.

I never understood how the AF one happened since the crew really would not know. Because I am a fairly regular customer on the GIG-CDG route I suspect the initiative may have come from check in because the agent did say "welcome back, Mr. jb, and happy birthday"