I use Python every day on the job, and often get new hires started on the learning track. Here's two resources I often use:
http://inventwithpython.com/
This is great for students in the FRC age range. It teaches programming/Python concepts through creating games.
http://www.diveintopython.net/
Also very good, targeted at users with at least a little programming experience (any language, really).
- Adam