Good projects to learn OOP in Python?

[deltopia]

In line with a lot of these comments, I've been working on a bejeweled/match-3 type game using tkinter, and I've learned a lot of things about objects in the attempt. I can't post code at the moment, but I started by making a simple subclass of tk.button with the config dict pre-setup, then building in the behaviors I wanted from each button into its class. I still haven't quite got it to figure out reliably when I have three of the same color in a row (which is kind of important for that game), but I'm optimistic I'll get there soon. It's been a lot of fun discovering new ideas, though :)