Daniel Lee's blog post details the development process of creating a Clock Panel plugin for Grafana 3.0, highlighting Grafana's new plugin system which allows for shared plugins via Grafana.net. The post covers the four types of plugins in Grafana—Datasources, Apps, Panels, and Dashboards—focusing on the panel plugin for displaying data on dashboards. Lee outlines the steps for setting up a development environment, writing JavaScript code for the plugin, using Angular and ES6 syntax, and integrating utilities like Lodash and Moment.js for date formatting. The plugin is styled using custom CSS and the post provides insights into publishing plugins on Grafana.net, concluding with plans for future customization features like adjustable date and time formats, colors, and countdowns.