Trello - Infinitely flexible. Incredibly easy to use. Great mobile apps. It's free. Trello keeps track of everything, from the big picture to the minute details.
BottomUp Skills - E-learning platform for innovators, creators, and creatives.
Curious - 15,000 lessons in tech, biz, DIY and more. Grow your skills.
Best of Machine Learning - A collection of the best resources in Machine Learning & AI
Indie Hackers - Connect with fellow entrepreneurs, developers, and bootstrappers who are sharing the strategies and revenue numbers behind their companies.
eLearnHero - Useful courses for entrepreneurs and startups