Batting order or lineup (sports teams and your own kinds of group): on a game's page, number the people who said yes. 1 goes first; leave a box empty to keep someone off it. Add a position or note if you like, then press Save. Everyone sees it on their own page. Nobody is emailed.
Who brings what (every kind of group except bands): on the event's page, type things to bring, one per line, and press Add. Add a comma and a number when you need more than one, like Drinks, 2. People press I'll bring it on their own page; pressing again takes their name off. You see who is bringing each thing, and can remove an item.