Justin Tadlock has a classic Justin Tadlock tutorial. I loved these back in the day. I learned the fundamentals of using CPTs, taxonomies, widgets, and more from Justin. If you read one thing this weekend, make it his latest tutorial on using the new term meta capabilities.
I’m going to walk you through building a simple plugin using term meta. What this plugin will do is allow users to assign a color to a category. This can be useful for all sorts of things. One thing that immediately comes to mind is designing a news theme and having a specific color associated with each category, which is typical of many news publications.