I think it would be very useful to have an easy way to get an average rating for the all the members of a group.  Obviously this average would change a lot as individual ratings change and members come and go.  However, a snapshot value for this at a given point of time is still very useful.

It would be nice if this could display on the group profile page.  But, due to its dynamic nature, being able to just query for it to be calculated would work.

This would be useful to evaluate a group you are considering joining, or for use for league/cup organizing.  Groups setup for learning/coaching could use this to target discussion to the average of the group...or track the change over time to see how the group is improving.

Again, just having the ability to query this at a point in time would be useful, even if nothing else was done with it.

Well, there you go...I didn't see that.  Thanks for pointing it out.