Send them a note.
Writing on her Harvard Business Publishing blog Change ... or Else!, Kanter suggests:
Send notes of appreciation to the people on your team telling them specifically what you value about each of them as colleagues. Surprise them with something they might not know that you notice. No form letters. Preferably hand-written notes, to stand out in the impersonal email clutter.A couple of years ago I was the recipient of such a missive, sent by someone fairly high in the organization. It was just a one paragraph, hand written note -- and it floored me. I've been a note sender ever since.
How do you tell your employees you appreciate all their hard work?