Looks like Shell is giving out buy one get one lift ticket deals for several resorts when you get 10 gallons or more of gas at Shell. Looks like there are black out dates at most resorts. Most notably, you can't use the deal on Saturdays at most of them. I've seen some spring break black outs too. Still, if you are a vacationer or local, this could be a good deal.
I remember last year I had some friends come out and we used the ones for Copper...however, we re-arranged the days where we were at certain mountains and ended up going to try to use the coupons on a Saturday.
Have used it a couple times to go to monarch. Here's a list of the resorts you can use it at: Skifreedeals.com | Resorts
Includes big name resorts like whistler, north star, stevens pass, Mt. Hood, winterpark, copper, etc.