Pay By Group is a way to organize a group and buy something -- whether it's a weekend in Tahoe or a big birthday present for a friend. It lets you coordinate and collect money from your friends, family, or others who you want to split a cost with.
Pay By Group uses a tipping-point model to ensure that everyone who you want to join in is actually committed before you complete the purchase. This way, nobody gets charged until everyone is ready, and nobody has to stick their neck out and be the first to pay.
Pay By Group saves you the time and hassle of figuring out who owes what, knowing who is really "in," and having to front all the money for a group purchase.