Minecraft JSON Text Editor
This is a JSON text editor for Minecraft. It generates /tellraw commands, which can be used by command blocks to add pretty colors, interactive links, and other cool stuff to chat messages. It is especially useful for maps, where you can use it to make tutorials, shops, and even interactive NPCs.
This editor, unlike others I've seen, has a what-you-see-is-what-you-get (WYSIWYG) interface. That means you can see and modify your command (almost) as it will appear in chat. It allows you to add colors, styling, links, hover elements, and entity scores to the resulting chat message.