Laylo - Create fan reminders for events, content, and merch

Meetup - Helps groups of people with shared interests plan events and facilitates off line group meetings in various localities around the world.

Attendize Event Ticketing - Attendize is a free & open-source ticket selling and event management platform

Eventbrite - Discover Great Events or Create Your Own & Sell Tickets

Zoho Backstage - Plan, run, and analyze your event— all from one place

Bigtent - BigTent is a web-based organization and communication portal for groups.