One area that has often been discussed as an EA or meta-EA cause area is rationality development, whether that be in the form of "raising the sanity waterline", providing relevant training to certain key people in order to empower them, or something else entirely.
What aspect of this strikes you as most interesting or relevant? What would you be most excited about seeing out of a new group or project in this area?
More thorough evaluation of productivity techniques, particularly those based on some form of group commitment/incentive that couldn't easily be replicated by a lone practitioner.
One aspect of this: Which forms of "standard" business training actually seem to work well? I've heard good things about Toastmasters; what about Getting Things Done training? Cialdini's courses on influence? People have paid a lot of money for these things for a long time, which is no guarantee of efficacy but still hints that they should be investigated.