Eventbrite - Discover Great Events or Create Your Own & Sell Tickets
Founders Nation - Find or become a startup cofounder
pretix - pretix helps you to sell tickets for your event in an easy way. It supports multi-lingual events and provides a wide range of features
CoFoundersLab - Meet 250,000+ entrepreneurs online
Ticket Tribe - Sell tickets online with no fees per ticket
Findnlink - Find people to work with on your ideas.