WeNvite

This is a very nice an useful app that can be used when you need to split the bill among your friends, colleagues, family or whatever type of set of people you can also invite people and one of the main features is that you can set the percentage of the amount you are willing to invite, let say you and two friends of you go out for dinner and it is one guys birthday so you and your other friend will invite! and then you spend $10 and your other friend spend $10 and the invited friend spend $12 so the invited friend will pay nothing! then the amount will be distributed between you your other friend equitably $6 and $6, so your final bill as well as your friends bill will be $16( your $10 + $6 you are inviting) you can also set a tip for the whole bill and will be applied individually for each spend, this application is very simple and useful. Let the app do the math.