Here it is, by popular, frustrated demand: the master list of every secret (or not-so-secret) keystroke in OS X, including all the keys you can press during startup. Clip and post to your monitor (unless, of course, you got this book from the library).
Note
For the most part, the following list doesn’t include the keystrokes already listed in your menus, like ⌘-P for Print, ⌘-S for Save, and so on.