Since Steven Moffat's probably going to commission a new Doctor Who logo when his tenure as showrunner starts, I decided to come up with my own ideas on what that could be:
http://lucasforums.com/picture.php?albumid=326&pictureid=2951)
This includes the Seal of Rassilon, as combined with the Garamond font, is meant to give a bit of an elegant look.
http://lucasforums.com/picture.php?albumid=326&pictureid=2952)
This was mainly meant to give a high tech look to the current logo.
http://lucasforums.com/picture.php?albumid=326&pictureid=2953)
This was modeled off of a logo I saw on DeviantArt, which featured a Cyan aura behind the text, in Arial Black.

Those are really nice. I like the 3rd logo, a lot!

I like the first.

Here's another:
http://www.lucasforums.com/picture.php?groupid=87&pictureid=3032) (http://www.lucasforums.com/group.php?do=picture&groupid=87&pictureid=3032)

It's been a while, but here's another one:
http://lucasforums.com/picture.php?albumid=326&pictureid=3335) (http://lucasforums.com/album.php?albumid=326&pictureid=3335)

And one more:
http://lucasforums.com/picture.php?albumid=326&pictureid=7900)