there are also a few extensions out there that let you not only set custom zooms for each page, but also allow you to crop off parts you don't want to be shown and it remembers your settings. Do a bit of googling I am sure you ll find them. You might also want to try the fabulous opera, or chrome and firefox, any of them much better than safari imho, what with the slow as molasses development of apple and the poor customization options.
edit: yeap that's the one that the previous poster mentioned, I had the tab opened for a while and hadn't refreshed to see someone else had replied... If you don't want the extension the simplest way is to go to preferences and set a stylesheet with default zoom set at a certain %. Google that for simple directions on how to do it.