The new icons in Leopard can be up to 512 pixels wide, but you are still limited to viewing them at small sizes in the Finder. By making a few small edits to some system files, you can make the View » View Options panel's icon size slider go up to 512 pixels, in order to show really big icons.
In your favorite text editor, choose Open... from the File menu. Type Command-Shift-G to enter a path to open, and paste in this path:
<object class="IBCarbonSlider" id="440">
<int name="controlID">1011</int>
<int name="controlSize">1</int>
<object name="layoutInfo" class="IBCarbonHILayoutInfo">
</object>
<boolean name="isLive">TRUE</boolean>
<int name="numTickMarks">8</int>
<int name="initialValue">48</int>
<int name="minimumValue">16</int>
<int name="maximumValue">128</int>
The last line is the key. You can change the number next to maximumValue to 512 and save the file. You'll be asked for an administrator password, as this is a system-owned file.
Mac OS X Hints
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