Startup 101 - TL/DR: Curated startup lessons for entrepreneurs who are looking to start a company as well as those in the process of building one.
Pramp for Product Managers - Practice product management mock interviews with other PMs
TopStartups.io - Backed by investors like Sequoia, A16Z, Benchmark. See the fastest growing startups in one place.
The PM Interview - Practice PM Interview Questions (w/ timer).
Zero To Founder - Micro Opportunities Handbook for Builders, Makers & Founders
Speechapp - The simplest way to practice for your next job interview