Chess Openings Trainer

I don't think this is a dumb idea at all. There is a need for a product that would be of service to many players. Seriously I think the Bookup (Chess Opening Wizard) made a serious run at this back in the day but I've not followed up with the current rev and a search for a similar question lead me to this thread.  I'm going to review the recommendations in this thread and hopefully get a bit further in my search. Thanks to all that answered and to the OP for asking the question. 

re: openings the games explorer here is a start, plus videos, articles, study plans etc.  lichess has a study feature in which you can save and download games and ideas.  chessable is a site where you can study openings via a flash card method, spaced repetition as they say.  CPT is a software that allows you to save and review your openings via a similar spaced repetition flash card method.  And chesspub and chess24 and chessopenings24/7 are opening theory sites.  so resources do exist in addition to the many books sold in all formats (pdf/chessbase/pgn/hardcover/kindle/epub) etc

Thanks for the great suggestions, it's amazing how little I know about what's out there.

Love this free program for PC https://sites.google.com/site/chessopeningmaster/

You set up the moves for white and black in any opening you wish to learn, add variations to main lines and run the practice. You can cement in your mind what to do and possibly become very good at a particular opening.

Chessable