The Sound On Sound “Classic Tracks” series talks about the production of famous songs in great depth, including insights into the songwriting, arranging and mixing: http://www.soundonsound.com/articles/ClassicTracks.php
How a mix engineer enhances a track:
Mixing “Superstition” by Stevie Wonder: http://homerecording.about.com/od/mixingyourmusic/a/mixing_superstition.htm
Alex Case - Setting up for a Mix:
These ARP Journal interviews with Producers include a lot of tips on mixing, both technical and philosophical: http://arpjournal.com/theme/interviews/
The consequences of “fixing it in the mix:”http://arpjournal.com/584/can-we-fix-it-%E2%80%93-the-consequences-of-%E2%80%98fixing-it-in-the-mix%E2%80%99-with-common-equalisation-techniques-are-scientifically-evaluated/
Mastering is the final sonic polish you give to a finished mix. The classic book on the subject is Mastering Audio by Bob Katz. Here’s a video teaser:
All videos were resourceful but for the last one on a mastering session. I particularly liked the videos on Phase. Technically critical, but also a wealth of creative techniques you can use with it.