Jigsaw (http://www.jigsaw.com/) is a business contact directory. This project is for developers using Jigsaw to write iPhone and iPad apps. It supports REST. The project also envisions support for on device object persistence using SQLLite.
TabSplit iOS is a native iOS app for the TabSplit, which allows users to view and manage their "social debts" on the go - view which friends owe you money, split a restaurant bill, pay back loans to your friends, etc.