The Y Combinator Database - The definitive database of YC companies with all the metrics
MilkDrop - 3D audio visualization plugin, compatible with WinAmp plugin API
Startup School - How to start a startup, by Y Combinator
projectM - projectM is an LGPL'ed reimplementation of Milkdrop under OpenGL.
Apply to YC (Y Combinator) - Curated collection of resources for founders applying to YC.
Magic Music Visuals - Fully-customizable and highly responsive visuals for live and recorded audio & MIDI.