I never even noticed Nokia's Dev site until now. It's so integrated with Windows 8 Apps, I don't know how I missed it. I wish I had seen it sooner.
They add challenges all the time, with points as prizes you spend on rewards, like gift cards or Nokia phones.
I'm pointing it out because one of the current challenges is referrals. "Each friend you introduce as a new user to DVLUP who completes an App or Upgrade Challenge will score you 500 PTS."
So if 2 people sign up and take part, I can get a $50 Starbucks gift card.