Lectionary is a simple iPhone application for following the Christian liturgical year. It presents biblical readings, feast names, and colors based on various interpretations of the liturgical calendar. It includes the lectionary and Collects from the Book of Common Prayer, including the Revised Common Lectionary, as well as adaptations of the RCL used by churches such as the Episcopal Church of the United States.
In a nutshell, Lectionary is a map of the Sunday and feast (Holy Week, etc) readings you would find during most of the worship services you might attend, with the ability to add the Daily Office if that suits your needs.
You can read more about Lectionary and Lectionary for iPad on the FAQ page.
Click the screenshots to see a larger picture of Lectionary on an iPhone.