This page combines several of my most often used visualization resources (besides stackoverflow). They fall into several categories such as plugins, web apps, tools and sites that showcase other people’s work. There are also two lists that function more as inspiration on Explorable Explanations and Storytelling with Data
This list of far from complete, but merely represents where I often find myself on the web during a project. If you have any good links / advice to add to anything to the lists on this page, please let me know in the comments and I’ll check it out!