ideas for a carpool app

carpool app

there are a bunch of carpool apps in the google play store, but they're not quite what I'm looking for.  they help arrange ad-hoc trips.  they use gps and such to compute how much each participant owes.  they don't generally work across platforms (I have iOS and Android participants)

in my carpool, participants don't pay each other; they just take turns driving.  that sounds pretty simple, but schedules being what they are, participants miss days, and often the driver is determined only by last-minute texting.

so a few things I'd look for in an app are:
 - a carpool consists of a route, a schedule, and two or more drivers.
 - counting rides given vs. rides received.  the next driver for a carpool will be the one with the lowest ratio.
 - calendar.  at a glance, you can see who will be driving on which day.
 - reminders.  the app notifies (possibly just texts) you when it's your turn.
 - confirmation.  you can tell the app that you're confirmed-in, or out.
   - other participants can see your confirmed status
   - if you bow out, the calendar will automatically reshuffle, possibly with notifications.

phase 1 (hackpocalypse time) would probably just be a mobile-friendly website, with notifications via email (-to-SMS)

or maybe phonegap

working schema:

carpool
 - id
 - departure time
 - departure place
 - arrival time
 - arrival place
 - schedule

schedule
 (this app is geared for recurring schedules)
 - days of week
 - holidays/exclusions

user
 - id
 - name
 - rides_given
 - rides_received
 - notify_info

driver
 - id
 - user_id
 - carpool_id
 - rotation_index
 - schedule of participation (e.g., M, W, F)

ride
 - date
 - carpool_id
 - driver_id
 - passenger_ids (postgres array column?!)