Startup School - How to start a startup, by Y Combinator
Mattermark - Ranking 800,000+ high growth Internet companies
YC World - Explore Y Combinator companies by country
Breakout List - A list of the fastest growing startups
Y Combinator Companies - Interactive list of all 1000+ YC companies
Crunchbase - Crunchbase is a platform for discovering industry trends, investments, and news about companies around the world.