In Ubuntu there is a toggle "Bigger text" you can activate, that's really comfortable when you have a big screen.
In Windows there is a wonderful option that make everything bigger in proportion, the size you like, and you don't have to care about anything else.
I can't find anything in the System Preferences but is there anything on OS X? After all they're the one selling 27" iMac everyday...
If not, is there something third party you would suggest?
EDIT1: Changing resolution does not help at all. If you do it, you will notice that the words get all more checkered and that makes them even more unreadable.