Lectionary for iPad is a simple application for following the Christian liturgical year. It presents biblical readings, feast names, and colors based on various interpretations of the liturgical calendar.
Lectionary for iPad is primarily a map of the Sunday and feast (Holy Week, etc) readings you would find during most of the worship services you might attend.
Lectionary for iPad also includes the Daily Office lectionary readings from the Book of Common Prayer - a reading for every day of the year.
For Sunday and feast readings, Lectionary for iPad includes readings from the Revised Common Lectionary for years A, B, and C. The RCL is very common with most mainstream churches, including Episcopal, Lutheran, Methodist, and Presbyterian, among others. If you are part of these denominations, chances are Lectionary for iPad will match readings from your church services on most days, or contain only a slight variation from what your church is using.
For those not using the RCL, Lectionary for iPad includes readings from the Book of Common Prayer in it's 1979 form. It also includes variations of the RCL specific to various churches, such as the Episcopal Church of the United States.
The Collects from the Book of Common Prayer are included in both Contemporary and Traditional forms.