See http://www.lectionarypage.net/ReverseLectionary.html for example.
Because of the way Faithlife has combined lectionaries and ordos into a single function, searching for passages results in extra results i.e. for every calendar year scheduled in the lectionary. A Reverse lectionary would solve that problem as well as providing information on passages not included in the lectionary - a problem the set functions of the passage list doesn't quite resolve. An example:
Orthodox Bishop Hilarion Alfeyev: "To be a theologian means to have experience of a personal encounter with God through prayer and worship."
I have some ideas for this, but I need to test them out. I'll get back to you when I've had time to do so.