[qwerty69]

Google Now will remind you when to leave in order to arrive to an appointment on time (as long as you are using Google Calendar) taking into account the local traffic situation. This one helped me already a few times not to miss a meeting.

[jwoah12]

I actually had an OpenTable confirmation in my gmail that wasn't added to my calendar, and Google Now still alerted me when it was time to leave. That one creeped me out until I realized it had scanned my email (still kinda creeps me out).