Currently on my Kindle – the iPad app and not the reader – among many other photography books is one by David Duchemin; Refining your vision in Adobe Lightroom.
This is not another Lightroom instruction manual, and David makes it clear in his introduction that it doesn’t mater if you use Lightroom, Aperture or some other RAw converter what he is discussing is his ethos behind workflow and post processing. It’s a very interesting read, I imagine David would be a fascinating guy to spend some time with.
It’s available in print as well from Amazon and you can download a sample Kindle version to wet your appetite.