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:

This includes the Seal of Rassilon, as combined with the Garamond font, is meant to give a bit of an elegant look.

This was mainly meant to give a high tech look to the current logo.

This was modeled off of a logo I saw on DeviantArt, which featured a Cyan aura behind the text, in Arial Black.