Just last night I was thinking that Reminders needed a "remind me at sunset" option to remind me to round up the animals. As it is I have to change the time of that reminder every month.<p>There are probably a ton of triggers that could be useful. Off the top of my head: time, location, weather, the people you are currently with (4sq checkins), current call, recent texts, or emails. I'm sure a bunch more.<p>I'm not sure that I'd call this a todo list, but it does sound like a GTD support system.