I prefer to drive from my office to Newark airport a different route then the driving directions on MapQuest, Yahoo Maps & Google Maps suggests. I prefer to stay on the Garden State Parkway, the whole way. In fact, if you hire a service to take you to the airport, they prefer to take you that way.
But I was never able to easily show people how to go that way, until now.
As the Google Lat Long Blog describes, you simply drag the lines to the roads you would like to take. I took a screen cast of my doing this for the route I mentioned above, here it is:
You can then overlay satellite imagery, traffic, hybrid, etc over your map, if you prefer and finally, give someone the link to your preferred route.
Forum discussion at Google Groups.