Lonely Planet Trippy
Lonely Planet's Trippy is a Google Wave Extension that helps you plan a trip with your friends using Lonely Planet's award winning content and Google Maps.
Google Wave comes with a built in Google Maps extension that lets you add a map to a Wave. With the built in extension you can place markers, create polygon shapes, search for locations and businesses and add them to your map. You can share your map with your contacts on Wave and they can also edit the map.
With Lonely Planet's Trippy extension for Google Wave you can plan a trip with your friends. Trippy allows you to create an itinerary of places to visit on your trip. Using Wave your friends can add locations that they would like to visit and they can vote on the suggestions already added to the itinerary.
Here's the introductory video: