Best ways to improve memory I've once watched a movie in which CIA agent went into a room just for a few seconds and on the next day he could recall every detail of that room, including what was on the monitors.

And I am wondering is there a way to improve my memory to this level?

I would also like to know if there are studied ways of accomplishing this.

There also is something that I remember reading few years ago about training visual memory: 

"You go into a dark room with a page of text and a flash light, and every ~30 seconds you turn on and off the flash light very quickly and try to recall as much as you can. And you do this for ~20 minutes. After ~30 days of practice you should have much better visual memory."

What do you think about this method. Could it really work? And if so, could this ability disappear after some time without practice?
Your best bet is to start looking on YouTube and the Internet for various memory methods used by card memorizers, magicians, and other stunt people.  I have used them extensively, and they work.  You can also look on Amazon for books.  Tony Buzan, Harry Lorraine, Dominc O'Brien. Also the book Moonwalking with Einstein.

Don't believe all the nonsense out there about your limited memory, or it takes years of practice, or you need special supplements.  I've met SEALs who used the simple techniques taught in the books to help them.  It worked for them.