Welcome back to Mac 101, our occasional series of tips for new and novice Mac users.
Over the past 25 years, icons may have become ubiquitous almost to the point of fading into the visual background; still, the little pictures that began in 32x32 black and white format have grown up quite nicely into the massive 512x512 icons we enjoy in Mac OS X 10.5 Leopard. Although the list and column views are more utilitarian for most file management tasks, there are times when icon view is the way to go.
You can control whether or not a particular Finder window displays in Icon view via the View Menu ("as Icons," or ⌘-1), and then adjust the display size of the icons via the View Options inspector panel (⌘-J). You can get up to 128px square icons in Finder windows, which is plenty big, but what if you want to see all the graphical power of those fully operational battle icons?
One way to see the full-size icons is via Cover Flow -- simply switch your Finder window to "as Cover Flow" (via the toolbar button, the View menu, or with a quick ⌘-4) and you can scale your icons at will by adjusting the window size. If you prefer not to have that black background around your icon, however, what is there to do? Thanks to Rob Griffiths at Macworld & MacOSXHints, here's a great tip for getting the maximum size out of your icon previews in the Finder without resorting to Cover Flow.
To view icon previews up to 512x512, hit the Spotlight search field at the top right of the window; search for a null string (two quotation marks next to each other, no space in between, like so ""), then change the search target from This Mac to Current Folder and the search type from Contents to File Name. Switch to icon view and you'll see, at the bottom right corner of the window, a scaling slider. Push it to the right to maximize your icon size. It's just the thing for appreciating the fine detail on your bottle of unicorn tears. (If you're looking for the CHOCK LOCK and Rick Astley icons above, they're in the QuickPix 2008 pack from the Iconfactory.)
Rob also hazarded a guess that we might see a more accessible version of this feature in future Mac OS X versions. If you watched the Snow Leopard stealth preview video posted earlier, you know he may well be right.