Google's new MyMaps is one of those features you could classify as "what a great idea and why didn't they offer this earlier?!' How many times have you told someone an address on the phone and suggested they find it via Google Maps or some other service? How many times did that person get it wrong? MyMaps solves that problem because you can do it for them and then share the map with others.
Besides the ability to share your maps, you can mark them up or add photos/videos to them. Every hotel, restaurant, etc., that currently lists directions on their website should take advantage of this; start with a simple map and add the photos and videos to show your customers what they can expect.
Think about the possibilities this offers for travel services and travel guides. It's not hard to envision an entire site-seeing trip, complete with video clips, all directed by your handy cellphone.