A Mac Zoom utility which magnifies a selectable portion of the screen and can be minimized.
If it cannot be minimized then the zoomed portion of the screen should be set as it is, so that i can do other work and switch back to it
In the Mac OS X Developer tools there's an app called "Pixie". It magnifies the portion of the screen under the cursor and can be "locked" on to a specific part of the screen. It has two sizes and can be minimized.
Im not really sure what you are asking for but the mac comes with a built in screen zoom tool its under System Preferences -> Universal Access -> Set the Zoom to ON then you the keyboard shortcut shown to zoom in and out
if you have a mouse with a scroll wheel hold down Control and scroll up and down and it will zoom in on the screen also.