Backstory: My friend's wife having a child next month and she plans to stay home for two years. She's worried that she'll have trouble finding work and she mentioned part time work would be the best.  

The Idea: A platform for parents to find part time work.

Deep Dive: You would build a simple two-sided job board for companies to post jobs and parents to find part time work. Given the specific niche it won't grow to be a unicorn company but there are riches in niches ;)

Both sides of the hiring/employment are on the same page with clear expectations. The schedule must be flexible and the work is ~20hrs per week.

Validation: There are a bunch of blog articles about trying to help returning parents find work but no dedicated platform.

Monetization: Similar to other job boards, you would charge the job poster a fix fee and upsell them on ad promotion.