Extravaganza - Airbnb for live entertainment!
Eventjoy - The Easiest Way To Organize An Event
Seatify - Reserve a seat at cafe & office from people there
Flyer by Paperless Post - Fun to create. Easy to share. Totally free online invites.
Guestlist - Market events online, accepting registrations & ticket sales
Event Hunt - Startups and Tech Events Curated By Locals