I have a 27" iMac and find that I need to use one resolution to read and another to edit photographs. This iMac's native display (2560 x 1440) presents text that is just too small to ready easily with my near-sighted eyes. I've always use Apple's Displays System Preference to switch resolution when needed. In my previous system, Snow Leopard (OS X 10.6.8), I enabled the Displays menu extra and clicked the icon in my menu bar to access the preference, but that functionality was inexplicably removed in Mountain Lion (OS X 10.8).
QuickRes is a welcome solution to your resolution woes. This screen resolution switching app from ThinkDev (formerly Inertiactive) gives you back what Apple r
