I was looking for a collection of free (preferably GPL-licensed) icons to use for a program I am developing. After some searching, I eventually found an article from Novell describing icons made by Ximian (a Novell subsidiary) for OpenOffice. However, the icons made by Ximian, like many icons in Linux, are in PNG format. Windows icons must be in ICO format.
Enter png2ico, an excellent program which, as its name suggests, converts PNG files to ICO. The PNG file I converted looks especially crappy, but I think I can live with it.