PalPark - Curate and share your learnings by topics
Indie Hackers - Connect with fellow entrepreneurs, developers, and bootstrappers who are sharing the strategies and revenue numbers behind their companies.
Golden - Mapping all human knowledge
Spectrum - Browser-based app to visualize the frequencies of an audio file.
LearnAwesome - Humanity's universal learning map
YC Startup Class - A live, one-hour class by Sam Altman on Platzi