I have found SDI (Strengths Deployment Inventory) to be a really valuable tool in leadership development, despite my being a skeptical curmudgeon about most of these workplace psychometric tools.
What convinced me was partly personal - I felt it offered valuable insight into my own self (not a pretty sight) - but also because of the impact I've seen it have within the training room. I've used it mainly for leadership development, so that's my main experience, and I've seen many people (not everyone) find it really useful in not only raising self-awareness, but more importantly giving them a roadmap for strengths development that remains true to their authentic self.
In the podcast Simon Gallon talks through the basic theory and its wider application within L&D, in particular in teambuilding and leadership development activities.
It's another long one, but it's good stuff.