I love my iMacs, but I was also frustrated working around the glare and reflections from ambient lighting. After watching some YouTube videos, I realized the problem wasn't the glossy screen, it's the glass cover that Apple puts over the glossy screen. By simply removing the glass screen, a lot of the glare and reflections were removed. Unfortunately, once you remove the glass screen, your iMac looks like it's part of an iFixit teardown.
So, I hired a local custom fabrication company to design a custom frame that goes around the edge of the screen. It took a couple of tries, but I was really happy with the way it finally turned out. In fact, I got such good feedback from the people I showed it to, that I decided to market them.
I've attached a photo below and here's my website if you're interested:
http://www.macframes.com