Loopple - With Loopple, you can build your next Bootstrap Dashboard easily using drag and drop.
Damn Good Tools - Easy-to-use, fun productivity tools—free (and open-source).
Chartmat - Build dashboards and apps on top of Google Sheets
Tool Finder - The wikipedia for 100+ productivity tools/apps
Launch - Free book featuring practical tips from top Product Managers
IT Tools - IT Tools is a free and open-source collection of handy online tools for developers & people working in IT.