"A strength and conditioning regimen devoid of gymnastics practice and skills is deficient."
- Coach Greg Glassman

You'll never run out of challenges for your rings. Again from Skills and Drills, this time still ring exercises. They are graded from A-E, A being easiest, E being most difficult. http://www.drillsandskills.com/skills/Rings/A

Five rounds for time:
400 meter run
10 pull-ups
10 dips

30-30-30 sit-ups
Tabata thrusters X 65 lbs.
30-30-30 sit-ups

Five rounds:
5 muscle-ups
5 presses to handstand