Apart from the X-Men series, there also has been a special focus on Wolverine, with two movies making it to the big screen - X-Men Origins: Wolverine (2009) and Wolverine (2013). All these movies, X-Men series and Wolverine, are criss-cross of stories and move back and forth in time.
Latest story of the mutants is X-Men: Days of Future Past. The movie has a raked in a whopping $261 Million global box-office opening.
Though I am not much impressed by the movie, it did pique my interest in the characters, stories and comics about the mutants. Here are some articles from around the web which I found while reading more about the X-Men -
READING LIST: ESSENTIAL X-MEN STORIES TO READ AFTER SEEING "DAYS OF FUTURE PAST
Thought X-Men was good, probably 7/10 but Prof X dies in the 3rd one and now he's just back in it, no explanation
— Matt Ridout (@mridout196) May 26, 2014
Here is another interesting article -
True origins of X-Men: How a second-tier comic inspired a legion of misfits and changed Hollywood
If you are interested in (being!) mutants like this lady is -
Watched x-men...and I hate the fact that I will never get to be a mutant. I'd be such a good mutant. I've never been so sure of anything.
— LZ (@LZLIANNAZ) May 26, 2014
If you need to read one article about X-Men, read this -
Ranked: All The ‘X-Men’ Movie Mutant Characters From Worst To Best