Bryan Bird/SuperTopo
A great, visually appealing guide to climbing in Zion. Covers all of the popular routes, along with a bunch of stuff you've never heard of.
Currently it's the guidebook for Zion.
The photos are beautiful, the topos are works of art, and the history sections are a lot of fun to read. If it were folio-sized it'd be a coffee table book.
You can get it as a printed book or as a .pdf file