Xobin - Most Comprehesive Pre-Employment skills testing and Psychometric Assessment Platform.
The Y Combinator Database - The definitive database of YC companies with all the metrics
Speechapp - The simplest way to practice for your next job interview
Startup School - How to start a startup, by Y Combinator
Pramp for Product Managers - Practice product management mock interviews with other PMs
Y Combinator Companies - Interactive list of all 1000+ YC companies