I don't drive around Boston a whole lot — the perks of working from home and living in a fairly walkable city — but when I do, it's often to specific locations: my roller derby league's practice space, "Fort Independence," for example, or my boyfriend's house. Apple provides an easy way to add bookmarks for frequent destinations, but the Maps app isn't so great at being able to see quick traffic estimations on the go. Asking Siri "How long will it take me to get to X?" will get you directions from the Maps app, but there's no quick way to preview travel time or routes.
Enter ETA: the $1 app and accompanying Notification Center widget not only stores your frequent locations, but gets accurate walking or driving time estimates for you from your favorite map app, too.