Have a tool that allows Captains to manage and check their team attendance for their upcoming games.
Allow Captain to send game reminder/notifications via email, and team members can respond by clicking "Yes - Attending", "No - Not Attending", "Maybe", "Going to be late", etc.
These email's can also be automated with some settings set by the Captain. E.g. Send automated reminder x days before game, on day of, disable automatic reminders, etc.
To take things one step further, have a team statistics section to track attendance of players (i.e. to see which players are regulars, and which players barely make it to games --> probably want to replace that person with somebody else next season)
Jonathan Burk commented
Please yes! Right now our captains have to use Whoozin or another RSVP site to see who is going to show up for the next game, and it's a huge pain. If the game reminder email could simply let the players respond about whether or not they're attending, that would be great!