This is a little treasure trove of Doctor Who videos from a little while back, commemorating the departures of David Tennant and Russell T. Davies and Julie Gardner from the show. First off, here's The Ballad of Russell and Julie:
Don't worry, Russell, I've been having dirty thoughts about Midshipman Frame too and I've managed to keep on functioning - o wait...
And here's David Tennant as himself, amongst the cast and crew and together with his musical heroes the Proclaimers:
Found here, with thanks to @scandalwomen.