Porridge is an extremely delicious food made by boiling oats until soft (thus it is often called "oatmeal porridge" and then mixing the result with milk, cinnamon, sugar, or anything you like until it is absolutely lovely.
There are other types of porridges out there (the dictionary assures me you can boil beans in water or milk and call it a "bean porridge") but they sound extremely nasty.
Here's a recipe for porridge that's certain to please: Three Bears Porridge. I cannot say for certain that this is the recipe that the Wizard and Widow Tattle use in In Pursuit of Porridge, but it may very well be.
Quaker Oats has a rather serious site, but a good one, save for calling "oatmeal porridge" the rather slangy "oatmeal" instead. The Cream of Wheat site is much more exciting in a nostalgic "I-can't-believe-they-haven't-changed-the-packaging" kind of way, but again, they don't use the word "porridge" very much, preferring the rather pedestrian "smooth and creamy hot cereal." It doesn't matter: we know they're talking about porridge.
If you'd like way too much information about breakfasts today from a marketing and business point-of-view, you can't miss this article from Food Product Design. Michael Foods, which is praised in the magazine article, has included it on their site (you can read about their "innovative egg products") and there's lots of tips for the aspiring "food product designer," an occupation I haven't really heard enough about. Read about "toaster wars," "phytochemicals," and a whole lot more.