Comic book letterer and logo designer extraordinaire Todd Klein has a fascinating blog about comic book logos. Here is a preview of my favorite of the many unused logos designed by Rian Hughes in 2006. Ultimately, Marvel decided to use a logo more in line with Jim Steranko's classic design.
(Note that the issue number and creative team don't actually correspond with the cover art for Uncanny X-Men 477.)
Here are links to Todd Klein's entire series of articles on X-Men Logos:
(The above logo can be found here in part 9)
Also, you can check out his blog for many more discussions about logos, comics, and life in general!: