Any books are eligible: non-fiction or fiction, running or non-running, or whatever...
This is actually too vast of a subject to ever narrow it down to ten, but I'll name ten I really like, in no particular order:
The Once and Future King - TS White
America - Jon Stewart
Angela's Ashes - Frank McCourt
High Fidelity - Nick Hornby
How the Irish Saved Civilization - Thomas Cahill
The Hobbit - Tolkien
Touching the Void - Joe Simpson
Reefer Madness - Schlosser
Cat's Cradle - Vonnegut
E=mc^2 - David Bodanis
The Autobiography of Malcolm X
2001: A Space Odyssey - Arthur C. Clarke
(#1) The Catcher in the Rye - Salinger
Honorable mention to: Advanced Marathoning - Pfitz and Douglas, as I've probably thumbed through that one more than any other book.
I couldn't do just ten after all.