While my phone (via Google Now) can remind me to do something when I am at a certain place, it would be quite handy if it could remind me to do something when I am with a specific person. That would require shared location data, but it would, occasionally, be pretty handy.
Mokalus of Borg
PS - Then again, I can probably solve that problem with a text and getting out of the house.
PPS - Unless it's a chance meeting before I thought I'd get around to whatever the reminder was about.