Matt screen to glossy screen
Yes, Virginia, there IS such a film. It's easily and cheaply available on eBay, and sticks to the matte screen by static electricity, so can be removed easily. (It leaves no residue whatsoever.)
I have used it on my Toshiba (Horrors!) L300 matte screen, and it actually DID give the screen all the zip and contrast of a glossy screen. I loved it!
but:
Your screen needs to be LITERALLY SPOTLESS when you apply it, as the smallest speck of dust will cause a visible "bubble" to appear, and you need to "squeegee out" air bubbles as you apply it for the same reason. Not only that, a tiny speck of dust will cause its little bubble to expand around it as it gradually pushes the gloss film away from the screen over a few days.
While I loved the effect, after two attempts, with a new film each time, and scrupulously cleaning the screen each time, the imperfections caused by missed air bubbles and dust specks annoyed me more than the matte screen did, so I took it off (again) and left it off.
But if you have access to a scientific "clean room" and antistatic cleaning fluid and gloves, I recommend trying it... It DOES work!
Mike