This post was published 4 years 3 months 11 days ago. Therefore, it may well be out of date. Do not reply on the contents of this post being accurate. Apple has included a nice set of high-resolution icons with Leopard. You can find these in /System/Library/CoreServices then right-click CoreTypes.bundle and click show package contents then, navigate to Contents/Resources.
The icons have a .icns file ending. You can open these in Preview and then save-as in the file format of your choice (.jpg, .png, .gif, etc.).
There’s one that makes me laugh – the image for a generic PC. I guess Apple just couldn’t resist.
