Foundler - Online hackathon weekends. Attend every other week.
Transferslot - Easily buy and sell side-projects
CoFoundersLab - Meet 250,000+ entrepreneurs online
MicroAcquire - A free & anonymous startup acquisition marketplace
Ship That Shit - Join 3 no BS events to help you ship that shit
1Kprojects - Neglected side projects for less than $1000.