Even though it was a mistake, it was amazing for the thousands who got in on it:
AMEX 50k points to add 5 authorized users. Each authorized user needs to make one purchase only to receive the points.
AMEX 50k points to do 15 transactions per month (10k per month).
Those are ridiculously easy, and the adding AU's was basically free 50k points. Not the MOST points/miles for a bonus, but definitely the best points/effort ratio IMO.