I just found out Catherine Tate -- Donna on Doctor Who -- interviewed David Tennant on BBC 4 radio, and it's online. I'm not sure this link will work but if you poke around the BBC 4 site for the show Chain Reaction you'll find it. The interview is pretty funny, as you'd expect. There's a lot of Doctor in him, and a lot of him in the Doctor. She's very funny, too. I'd love to hang out with the two of them for a while... Oh! 19 minutes in they talk astrology. He's the greatest man in the history of history.