Apparently I am engaging in some sort of deviant workplace behavior.
I like to email short notes to people when they strike me as particularly awesome -- and cc their boss. I never do it unless it's sincere, but it's not hard to find opportunities; we have a great staff and examples of well done projects or just general greatness abound. Sometimes I send the note to their boss directly, with the person I'm talking about cc'd.
It's weird how unusual this seems to be.
Why aren't more people doing this? It makes people feel good, it pretty much guarantees that they'll keep up their awesomeness since everyone wants to be as cool as others think they are, they'll be more inclined to help you out in the future, and it might inspire other people in your office to start doing the same thing, which could actually have a not insignificant impact on how nice of a place it is to work.
Seriously, send a note today to someone who you think is a rock star. Stick their boss in the cc field. If you can't think of anyone who deserves this, send it to someone great who you deal with at another company (and then start plotting your escape from wherever you're currently working).