Super-Size Dock Icon Magnification
For those using larger displays you may wish the Dock icon magnification was greater, this can be achieved easily with a defaults write command. The number at the end represents the pixel dimensions of the icon magnification, so 200 equates to 200×200 (for reference, 128 is the default):
defaults write com.apple.dock largesize -float 200
200×200 makes the icons quite a bit larger, but you’ll start noticing pixelation because Mac OS X does not yet support resolution independence. For you to see the changes, you’ll need to have Magnification enabled through System Preferences > Dock > Magnification, and then you’ll have to kill the Dock:
Other than aesthetic reasons, larger magnification can be useful when setting up user accounts for novices, the visually impaired, or kids. If this is your objective, you might want to go a step further and create an iOS style desktop for the Mac.
Beyond a point this really isn’t that useful and it can turn just downright useless and even ugly as icons get pixelated, case in point:
defaults write com.apple.dock largesize -float 512
Other than for pranking someone, this looks basically ridiculous. The image below shows 512×512 Dock icons laying over System Preferences:
As you can imagine, when icons are 512×512 they’re taking up a considerable percentage of your average Mac screen, which becomes a usability disaster for anything beyond humor.
You can revert back to normal again by setting a maximum of 128:
defaults write com.apple.dock largesize -float 128; killall Dock
That last command combines killing the Dock with the defaults write into a single string, just makes things easier.
Along the same lines to this, you can also super-size Desktop icons to outlandish levels with a different defaults write command, but it suffers the same pixelation issue.