App Launch Checklist - Planning tool for launching your app successfully
Y Combinator Companies - Interactive list of all 1000+ YC companies
Startup Toolkit - Interactive how-to guides to launch your startup
Apply to YC (Y Combinator) - Curated collection of resources for founders applying to YC.
Submit Checklist - Checklist of directories to submit your startup
Startup School - How to start a startup, by Y Combinator