Travefy - splits payments in advance and helps coordinate group trips - this is probably our closest competitor
WeTravel - is a tool for planning and promoting trips, but is more focused on situations where the planner does everything and might be getting people who they don't know to come on the trip (i.e. yoga retreats) vs. collaborating with friends
ComboTrip - Their specialty is helping people discover activities, lodging etc. on their trips and making agreed upon decisions, doesn't have payment component
Triporama - supposedly a group planning app, but the site appears to be down
Sports Basement - renting from Sports Basement saves you money and time on the mountain so would also be the consideration set, could also partner with them
Uber Skis - will give you and your skis a ride to the mountain
Luggage Forward - ski shipping service that will also send your skis to the mountain