The Bosco - High tech photo-boothing for any event
Meetup - Helps groups of people with shared interests plan events and facilitates off line group meetings in various localities around the world.
MinglePic - Share your event photos with everyone at the party
Event Hunt - Startups and Tech Events Curated By Locals
Party with a Local - Party with a Local is a free app that connects travelers with locals that want to party.
Eventbrite - Discover Great Events or Create Your Own & Sell Tickets