Wawa recently started carrying K-cups for their coffee blends- Sheetz should do the same and also sell them online for those that do not live near a Sheetz
Specialty Coffee/Frozen Drinks
I think ice cream sodas would be awesome. Like legit ice cream with soda mixed or pumped in.
When customizing lattes, cappuccinos, etc on MTO, it would be nice to be able to choose more than just one flavor. If there is already a way to do it, I surely haven't figured it out.