Flippa - Flippa is a platform for trading websites.
Makerlog - Makerlog is the dead-simple task log that helps you stay productive and ship faster.
Transferslot - Easily buy and sell side-projects
MakerWidget - An embeddable portfolio for your (side) projects
buysellwebsite - Created by two California attorneys, WebsiteBroker.
Indie Hackers - Connect with fellow entrepreneurs, developers, and bootstrappers who are sharing the strategies and revenue numbers behind their companies.