Diagrams for Mac - A diagram editor for visualizing structures and processes
Figma Product Planner - Easiest way to plan, visualize, & share your product planing
The Data Visualisation Catalogue - Reference tool for data visualisation
Sortfoo - Curate lists of products, places and information.
nivo - nivo provides a rich set of dataviz components
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.