Product School - The global leader in product management training
ClevNote - ClevNote is an amazing mobile application that helps you to write the daily memos on your smartphone.
The Product Manifesto - Product Managers face the biggest challenges of our day, which is why our community needs a common set of product principles.
Notes with pictures - Notes with pictures is one of the best mobile apps that enable you to write notes and add images, voices, videos, and attach documents to your records.
Intercom on Product Management - The ultimate resource for aspiring product managers
Notepad by Splend Apps - Notepad by Splend Apps is one of the best mobile apps that enables you to create a to-do list and notes.