Text your SO when start your commute home!
I saw an Applet for something like "text my wife when I leave work" which sends a text when you exit an area. This works OK, but it also texts you're spouse if you go to lunch or to an off site meeting! This Applet is a variation. Pick an area that's on your home commute to text your SO. I commute by bike, so I picked an area on my bike trail about one minute outside of work. When I hit that point, my wife knows I'm on my way, and I'll be home in 20 min.