Call me crazy, but I'm sure I remember this capability existing in previous versions of Windows. In Windows 7, we can have file extensions Off... or On. Pick one. Is there some obscure switch buried in the registry to have Explorer show specific extensions, but leave the rest hidden?
In my case, I'd like to always show extensions for text files (*.txt, *.csv, *.tdt), because I frequently have to handle flat files which may come in with a .txt extension where I need it to be .csv, for example. I'd rather not have extensions on all the time, it's just clutter for almost all files.