List Manager is part of the guestmanager.com suite of tools for event management.
List Manager is for staff and promoters of event organizations to manage their own guest lists. whereas the Guest Manager app (also available on the App Store) is for at the door checkins and barcode scanning.
Use List Manager up until your event date to make sure that the right people are on the list.
With List Manager you can add guests in bulk using copy/paste, select contact(s) from your address book, or even choose your facebook friends! All names are synced in realtime to the Guest Manager app for checkins, so you can be sure the list is always up to date.