Indie Hackers - Connect with fellow entrepreneurs, developers, and bootstrappers who are sharing the strategies and revenue numbers behind their companies.
NumWorks - The graphing calculator that makes learning math easier.
Starter Story - Learn how others are building successful e-commerce businesses.
Learney - Knowledge aggregator for developers
Maker Stories - Discover the stories behind products
eMathHelp.net - Site is created to help people learn math. Includes algebra, calculus, differential equation calculators and notes with many examples.