Credito is the first App design that I have come across that approaches this problem from both a user education angle as well as a vendor integration angle and marries the 2 to solve the problem.

Picto is the first App design that I have come across that solves the needs of a group of people playing Pictionary. It balances features with flexibility and reduces the probability of arguments like no other app on the market.

Design an app that helps users buy gifts for friends/family.