Chase (link here): First two rides = 50% off (up to $15 per ride). Use your Chase card to sign up for a new Uber account, enter promo code CHASE50, and take your first two rides by 7/31/17
SPG (Starwood preferred guest): this is target offer. I got it in the email, quoted below:
Get started with Uber. Enter promo code SPG2017 during sign-up or on the Uber app “Payment” page, and you’ll enjoy your first ride for free (up to US$20*). Offer valid through March 1, 2018.
Amex Platinum (“How to Get $200 in Uber Credits From Your Amex Platinum Card” by TPG): I don’t have the Amex Platinum.
Note I live St. Louis, in which Uber has not grown popular yet. But I plan to take it sometime this winter.