While this isn't directly related to parkour, everyone gets injured and/or sore, and these books have been tremendously helpful. They also saved me a ton from what I'd spend on sports massage.
The Trigger Point Therapy Workbook
taught me how to massage trigger points to reduce or remove pain from strained necks, shoulders, wrists, ankles and knees... and just about anything that gets sore - even migraines.
Accupressure's Potent Points
covers most everything else, sinuses, fatigue, nausea, etc.
For full disclosure, I get a whopping dollar through Amazon Affiliates if you buy through the links.