DUBL - Simultaneous front & back smartphone video app
NumWorks - The graphing calculator that makes learning math easier.
HiringPlan - The headcount planning tool with built-in market data
Learney - Knowledge aggregator for developers
AngelList Track - Mission control for recruiting.
eMathHelp.net - Site is created to help people learn math. Includes algebra, calculus, differential equation calculators and notes with many examples.