Parent Hacks has a nice Google Maps hack:
Every time my son gets invited to a friend’s house or a party, or if I even just pick up someone to take with us somewhere, I go to Google Maps, print up a copy of a map to their house, write the child’s name, phone number, address, and parent’s names on the printout. I then fold it up and paperclip it with the group of others in the glove compartment of my car. That way, it is always there when I need it at the last minute (which is when my son plans most of his outings). It is even there for “emergency” situations when I need to quickly call a parent if I’m late.
I did this last soccer season to keep track of the multiple fields I was trekking to all the time; they went right into a thin three-ring binder that fit nicely underneath my seat.