Validated ideas - List of 5,000 poorly executed but popular apps
NicheGenerator.nyz - A funny solution to start with people, not ideas or products.
Burner Page - Validate ideas with burner pages in < 60 seconds
Idea Crunch - Successful business ideas not yet launched in your country
Building the Right Mobile App - A free email course on validating your mobile app ideas
The Idea Generator - A tool to help structure your business idea brainstorming