The bibledesktop_icon_*ai are Photoshop Illustrator files.
The *png files are provided exports of the *ai file.
The book-icons.xar is a Xara Extreme file.

The ../jnlp/BibleDesktop128.gif file is used by jnlp.
The ../installer/macosx/BibleDesktop.app/Contents/Resources/BibleDesktop.icns is created on the Mac using IconComposer (Tiger) or Icon Composer (Leopard)
To create ../installer/win32/BibleDesktop.ico use http://tools.dynamicdrive.com/favicon/ with the *_icon_64.png. Check both boxes to merge with larger sizes.

Put a copy of BibleDesktop.ico in bibledesktop-web/src/web/images.