<p>Milestone keeps a stopwatch-style record of the days since you quit smoking, the hours until you say &quot;I do,&quot; the billions of seconds since you were born--a simple yet staggering level of detail. Just don't get caught peeking at the app when someone asks how long you've been married. (<a href=&quot;https://itunes.apple.com/us/app/milestone-celebrate-moments/id794876340?mt=8&quot; target=&quot;_blank&quot;>iOS</a>)</p>