The name of the show is "Doctor Who" NOT "Dr. Who". If you are referring to the character, New Who is very clearly "Doctor". While Old Who did use "Dr" in the credits occasionally. Since I love the new series so much, I'll stick with "Doctor". And while we are at it. His name isn't "Doctor Who", it's "The Doctor".
“Doctor Who: You want weapons? We’re in a library. Books are the best weapon in the world. This room’s the greatest arsenal we could have. Arm yourself! (from Silence in the Library episodes 8/Season 4)” — Russell T. Davies
The TARDIS Ring: Yes, I Vow to Spend Eternity Traveling Through Time and Space With You. Best marriage proposal ring ever. If a guy gave me this I'd say yes in a heart beat. Not because its a wedding ring, but because he knows my heart.