I just received a notice from Delta that their newest travel partner is Airbnb. According to the message:

INTRODUCING OUR NEWEST PARTNER, AIRBNB.

Now earn 1 mile per $1* spent at more than 2.5 million homes around the world. Plus, new guests get a $25 Airbnb coupon code and earn up to 1,000 bonus miles with their first qualifying stay.

Interested in becoming a host? Earn up to 25,000 bonus miles to help fuel your next trip.

Learn more and earn miles exclusively at deltaairbnb.com.

I believe Amex also has a relationship with Airbnb. Maybe an opportunity to use a Skymiles Amex for your Airbnb stays and earn even more points/miles?