Colo (Masaru Kaji) of Colo's Junk Room is working on tutorial to explain Class Modules. (As mentioned before, I used a Class Module for the first time at Colo's suggestion for my Cell Spotter add-in so you can assume that I'm very interested in learning more about them)
It's still a work in progress. At this time, two chapters have been uploaded and a third is on it's way with more to come at a later date.
As with all his tips, Colo doesn't just show the code but explains in detail how things actually work. Understanding the theory itself makes it a lot easier when it comes to developing your own stuff.
I'm happy to include Colo's tips as a permanent addition to my side bar. There's always something new to see, something new to learn. Please become a regular visitor like me ;-)
P.S. Colo's VBA Tips also has a RSS and XML feed so you can see when new tips become available using his EaZy RSS reader add-in, available on his Downloads page.
You can use it while still using Excel but don't forget to set it to "Ninja Mode" if you are using it at work!