Pool money online for a road trip

You and your friends have been talking about going on a road trip one summer ever since you could drive. You've come up with a roadmap with all the places you want to hit along the way and run the numbers on what you'll need. Now you just need to get the money from your friends so you can have it all in one account for the trip. Getting that money has been harder than expected, since you guys don't see each other as often as you'd like and everybody's always forgetting.