Siftbot's congratulatory message on my profile when I became Ruby made me realise that the single powerpoint awarded doesn't really seem like enough of a reward (ignoring new powers and privileges here).

I propose something along the lines of:

Bronze - 1 power point
Silver - 1 power point
Gold - 2 power points
Ruby - 4 power points
Diamond - 7 power points
Bronze Crown - 10 power points

I say, upon reaching new star levels, give people a bunch of powerpoints to spread some celebratory qualities and promotes upon their fellow sifters.