Never underestimate the power of the most senior person in the organization dropping by your office/desk, unannounced, and saying "Don't worry about the mess. This is not a big ceremony, and you're certainly not getting fired. I just wanted to thank you for doing X. Terrific job. Really helped. We're lucky to have you." No grandstanding, no plaques, no speeches, no trips to the podium. Just a simple personal thank you from someone who matters and has the birds-eye view of the organization and its outcomes.