One persistent problem I used to face while using GNU/Linux was when I visited sites containing certain flash based games. The games played well but they never displayed the text embedded in it. I thought that it was a drawback of the flash player ver 7 provided for Linux. It never occurred to me to dig into the problem and find why it was happening so.
But recently, in the process of installing a software package, I installed all the core Microsoft fonts on my machine running Linux. In Ubuntu/Debian, there is a package called msttcorefonts which bundles all the most common true type Windows fonts. You can also copy the fonts from your Windows partition to Linux if you are dual booting between the two OSes. Once the fonts were installed, I was pleasantly surprised to see the above mentioned problem disappear.
That was when it struck me that perhaps the flash game in question could be using a Windows specific font to render the text in the game. And since there are no Windows fonts on a default Linux installation, the flash game/site is unable to show the text.
So the next time you visit a flash site and can't see any text, be sure that it is because you don't have Windows fonts on your machine running Linux.