Tomorrow, Thursday, at 8:00pm I will be giving a class in Mayan Yisroel of Flatbush (3315 Avenue N, Brooklyn, NY 11234), discussing the Halachos of Ribbis as they apply (or don't apply) to lending out a Credit Card to a friend.
Specifically: When you lend out the Credit Card to your friend, and he (hopefully) pays you back, are the miles you get considered Ribbis? If not, Why?
The class is part of a new series of Halacha classes I will begin giving there, which will cover interesting topics in Halacha.