Google Groups - Google Groups allows you to create and participate in online forums and email-based groups with a rich experience for community conversations.

JustRSVP.me - Online Invitations and response tracking for weddings, baby showers, birthdays, parties, and other...

DownToMeet - DownToMeet is a platform to organize, find, and attend group events.

RSVPify - A powerful and awesomely customizable platform for selling tickets online for your event.

Mighty Networks - Mighty Networks enables entrepreneurs, organizations, and companies to create and grow a community-powered brand.

Evite - Send online invitations for all occasions by email or text message. Create invites for birthdays, baby showers, save the dates, or customize your own design.