XnView.com - (Free)
XnView is a photo viewer software that offer features other than viewing, including converting graphic files.
XnView is a software specially designed to enable user to view any graphic image. This software can recognize more than 500 file formats including 500 in reading and 50 recording; it can read standard formats such as JPG, GIF, TIFF, GMP, specific formats such as SIL, BOB, or proprietary formats such as Photoshop, Corel Draw, etc. XnView also allows to edit images, offering the possibility to crop an image, rotate it, redefine colors, and more. User can also add filters and apply effects . Besides playing all files in these formats, XnView is a tool that can perform bulk operations on the files such as batch conversion file, reducing the size, the application of filters, and many others. This software is able to use Photoshop filters, to make screenshots and create HTML galleries.
User is also able to create slideshows, thumbnails, make screenshots, batch conversions, and much more.