If you don't use any of these keyword, then please do not present yourself as a C++ programmer at all. Some are quite infrequent - I've never used "auto", "register" - but I can't think about any serious C++ OOP code lacking "explicit".
The auto keyword has been repurposed to do some basic type inferencing. It helps save a lot of typing (both senses of the word apply here). This is in c++0x and most compilers already implement this usage of auto.
I am not a good or a professional C++ programmer by any means, but still I find these quite basic. I think you will encounter them in the first 5 items or so of Meyers.
Has anyone here actually seen (or written) C++ code that used the and, not, or or keywords (from iso646.h)? These keywords seem cleaner and are standard, yet I have never seen (or dared use) them in practice. In my day job, I write code that must be portable across a dozen platforms, so I am paranoid about using "unusual" C++ features.
Kind of reminded me what a gigantic, arcane mess C++ really is. It's not enough that there are half a dozen different semantics of "const" -- the "mutable" keyword let's you break the convention of the const function (not changing member values) without a user of your interface ever knowing about it.
Isn't it the cost of having direct access to the memory? Can you name another language where you can control so many aspects of the system, and still remain "clean"?
And a true C++ programmer can name ALL the uses of the 'static' keyword.