Viable Fit - Measure and improve your product market fit
upcoach - The platform to scale your group, cohort, or 1-on-1 coaching
Product Fit - Measure product/market fit in app with your users.
Tribe of Mentors - Short life advice from the best in the world, by Tim Ferriss
Product/Market Fit Survey - Check how close your product is to Product/Market fit
MentSpot - Find a mentor or become one for free