The SlideShare Delhi team had an offsite recently (May 20-22, 2011). We went to the fabulous Robber's Cave, which is midway between Dehradun and Mussorie. The team put up at the scenic Rio Resort (http://www.rioresort.in/) which is a stone's throw from Robbers' Cave.
It was three days of fun and hoopla, away from the daily grind. Check out the pictures here.
Both Robber's Cave and Rio Resort are awesome - highly recommended for anyone looking to rewind outside Delhi.