IrfanView is a image viewer for Microsoft Windows that can view, edit, and convert image files. It allows to open a wide variety of image formats and displays thumbnail file previews, allowing picture organization and management.
Some IrfanView features:
Many supported file formats
Multi language support
Paint option - to draw lines, circles, arrows, straighten image etc.
Toolbar skins option
Slideshow (save slideshow as EXE/SCR or burn it to CD)
Show EXIF/IPTC/Comment text in Slideshow/Fullscreen etc.
Support for Adobe Photoshop Filters
Fast directory view (moving through directory)
Batch conversion (with advanced image processing)