Why wouldn't you just forward them a link to the driving directions page? You lose all the functionality of the awesome Internet we have in 2010 by sending someone a static map. Anyone who can receive that would be in front of a computer connected to the internet, or if they are on the go, would be on a smart phone with internet access so they could look it up themselves. Might as well just carry around a paper map.

Unless you want to be a doormat like that guy in the commercials whose friends call him to ask him for driving directions and movie show times because your phone lets you browse the web while you're in a call at the same time. Let your friends look up their own directions.