This module requires the event module and defines a new event-enabled node type "event with volunteer time slots". Site users can sign up for particular times, and event organizers (and those with the admin permission) can also add users to or remove users from the schedule.
An automatic e-mail reminds signed-up users about the upcoming event (requires cron to be configured). See the REAME file for more details. An important feature revolves around display of a volunteer roster than can be viewed by the event organizers and which can display fields from the profile module and provides a text field for notes about each volunteer.
Note: a PostgreSQL schema is included in the install file, but I have not yet been able to test it. Please submit comments or problems in the issue tracker.