I was at my LHbS today and saw this method for carbing a keg that I had never heard of:
1. Once keg is sealed with home brew refrigerate to 40F
2. Connect CO2
3. Adjust CO2 to add 20 PSI
4. Zap keg by agitating rolling or shaking for 2 minutes
5. Disconnect CO2
6. Refrigerate for 5 house
7...