Meetup - Helps groups of people with shared interests plan events and facilitates off line group meetings in various localities around the world.
Sun Surveyor - Sun Surveyor calculates Sun and Moon Positions, Sunrise & Sunset and Moonrise & Moonset...
Facebook Local - Discover places to go and events happening near you
Natural Hour - A roman timekeeping add-on for Suntimes.
Eventbrite - Discover Great Events or Create Your Own & Sell Tickets
Sol: Sun Clock - Get reminded when it's sunrise or sunset, wherever you travel!