The David Tennant Treat 4 Today is a photo which Sunshine (I think) posted on GallifreyBase.com a couple of months ago.
It's a photo of David Tennant as The Doctor during filming of The Girl In The Fireplace. It's a behind-the-scenes-photo but the best thing about it is the gleeful and childlike expression on David's face!
This is one man who enjoys his work!
As always, click on the photo for a larger version and if you would like to suggest a David Tennant Treat 4 Today please email DavidTennantOnTwitter@gmail.com