1) Free image viewer 
KSquirrel is an image viewer for the KDE desktop environment with a disk navigator, file tree, thumbnails, extended thumbnails, dynamic format support, DCOP interface, KEXIF and KIPI plugins support. The current version is 0.8.0 (Dec 07 2007). It supports more than 57 image formats, including PNG, JPEG, PSD, APNG, GIF, WMF, OpenEXR and many other....