Google Open Source - All of Googles open source projects under a single umbrella
The Y Combinator Database - The definitive database of YC companies with all the metrics
SmallDevTools - Handy developer tools with a delightful interface
Startup School - How to start a startup, by Y Combinator
whatdevsneed - This is whatdevsneed.
Y Combinator Companies - Interactive list of all 1000+ YC companies