One of the better eBook answers out there is The Lightroom Queen's (I don't make this stuff up) Adobe Lightroom 5 — The Missing FAQ. There are also versions for Lightroom 1 through 3 if you're still using those. You can also order this book from Amazon (affiliate link) and help support this site:
As you might expect, both Scott Kelby and Martin Evening have pretty good Lightroom books. I'm basing my Lightroom 5 recommendations initially on the Lightroom 4 books that have appeared:
- The Adobe Photoshop Lightroom 5 Book for Digital Photographers (affiliate link) by Scott Kelby
- The Adobe Photoshop Lightroom 5 Book: Complete Guide for Photographers (affiliate link) by Martin Evening
At the moment I'm looking at several books on Aperture. When I've completed my survey I'll add any recommendation here.