Here are some interesting Google Maps mashups (courtesy of Wired magazine)... they make me want to design one!

• Flood Maps - how the world will look if the sea level rises
• Fast Food Maps - well designed interface
• Mappy Hour - happy hour locater
• Urban Drinks - another happy hour locater (better interface IMHO)
• Safe2Pee - bathroom finder
• Gmaps Pedometer - one of the original mashups, still good!