The Y Combinator Database - The definitive database of YC companies with all the metrics
Startup Stash - A curated directory of 400 resources & tools for startups
Startup School - How to start a startup, by Y Combinator
Makerbook - A directory of the best free resources for creatives
Y Combinator Companies - Interactive list of all 1000+ YC companies
Freebiesjedi - Discover & download useful freebies everyday