Bill Ninja makes splitting bills quick and easy. With support for three different types of bills the application lets you split the bill and customize the amount due from each payer. When you are done you can share the bill via email and save it for future reference. Bill Ninja allows you to split the following types of bills:

Dining Bill - Enter the amount and optionally use the simple built-in tip calculator to rate your service to compute your gratuity and update the total.
Itemized Bill - Create a custom bill consisting of one or more items, then split the total. Great for sharing the costs of a weekend-getaway for example.
Monthly Bill - Bill Ninja makes it simple to amortize monthly bills like utilities or cell phone service.

The app integrates with your contact list so you can easily email bills to your contacts. Advanced features let you copy bills which you can then edit to create new bills based on previous distributions and payers. And course you can pin bills to your start menu for quick and easy access to individual bills.