At work I have to use Windows. (At home I use a MacBook Pro so there are basically no danger keys.) While currently I only have the keycaps for F1 and INS removed, in the past I have also pulled F12, caps lock, and the Windows/menu keys. I just leave them in a small plastic bag next to the keyboard.
I don't know how you missed the Windows menu key, since it yanks focus away from your current program if it gets tapped by accident, then you have to waste time getting back to normal. It's almost as bad as F1.
The insert key is bad if you have an editor that tries to implement "overwrite mode" in a mouse-based text editor, which is pretty silly. It can also rarely get engaged by pressing the keypad zero key under certain conditions. (like with the shift key hald down, I think)
Actually there is one important danger key with OS X. I don't know why UI implementers insist on being able to do all sorts of file manipulation functions in contexts where you are supposed to be selecting or viewing a file (instead of, you know, switching to the file manager program), but they do. Windows goes out of its way to support moving and deleting files when you need to select a file, and various OS X programs insist on deleting a file whenever you hit command-delete (aka command-backspace).
The problem is that command-plus and command-minus are used for zoom in and out. (Very useful in the Preview.app image viewer.) Be off by one key when zooming in, and your file is suddenly moved to the trash, and its window (if it has one) closes. In a file viewer program. WITH NO UNDO AVAILABLE. WTF. Now you get to fish it out and put it back where it belongs. At least it also insists on playing a (non-configurable!) sound when it does that, so you can have some idea that something has happened.