Best resources for learning.

[Christopher149]

Pneumatics: http://www.team358.org/files/pneumatic/ (gets into all the gritty detail)
Suppliers: McMaster-Carr, Andymark, VexPRO are some biggies
Controls: well, the 2015 system will be RoboRIO, so we'll all be rookies to a degree

[Basel A]

You should be able to find information on most things by searching through Chief Delphi. Here's a few examples:
Lifts and Arms from SCRRF Workshops 12/15/01
Elevators: Cascaded vs Continuous
Drivetrain Physics
Michigan State Championship Seminar Series videos

Many teams have resources on a section of their website. Here's a few of the best:
http://moe365.org/resources.php
http://www.simbotics.org/resources
http://www.indianafirst.org/resources (not exactly a team, but whatever)

You can learn a lot from what others have done in the past:
http://www.hotteam67.org/engineering-design/
Killer Bees 2011 Robotics Season Journal

[Monochron]

I hate to self promote, but I recently made this motor reference sheet that may help you when deciding what motor to use for a specific task. It has specs for most every motor and gearbox common in FRC, lists which motors are compatible with which gearboxes, and lists useful equations for converting torque to linear force and the like.