Black Blocks - Validate first.
Litebulb - Get your ideas out there
Lean Canvas - Business plans take too long to write, are seldom updated, and almost never read by others but documenting your hypotheses is key. Lean Canvas solves this problem using a 1-page business model.
Microns - Microns.io is a marketplace to discover the best micro-startups for sale.
Idea Validator - A customer development tool to help you validate your ideas before building them.
earlyStage - Meet the co-founders and investors of your future startup