Has most of the features that programs like irfanview have, like thumbnailed view, manipulate settings like brightness and size, flip images and adjust colors. Best of all, its free and fast to use. An alternative to irfanview and xnview.

Update: The Forcevision Image Viewer is no longer available. The developer website has been discontinued and it is likely that the developers have stopped development some time ago. Windows users looking for an alternative image viewer should take a closer look at the excellent XnView.

XnView supports hundreds of different image formats. Even better: The developers release new versions regulary, and it is not only available for the Windows operating system but also for Linux, Mac OSX and various smartphones.

XnView is available here on the developer website.

A second alternative is the Fast Picture Viewer which has been specifically designed for photographers. It is one of the fastest image viewers available. Support is great with support for more than 45 different image formats and more than 370 different camera models and their RAW formats.

Some of the advanced features for photographers and image editors and inspectors are IPTC Editor, RGB histogram, Color Management, EXIF, Tethered Shooting and ultrafast Raw previewing.

Fast Picture Viewer is available as a 32-bit and 64-bit edition for the windows operating system. Windows users should download the cheat sheet in pdf format from the developer website to learn the ins and outs of the image viewer and rater.