First Impression is a free, lightweight image viewing app that is geared towards utilizing as much of the screen’s real estate as possible for image display without cluttering it with the viewer’s own interface. It manages to do so while providing a nice set of functions, but what I really like about this program is that images are displayed on screen as draggable objects (similar to previously mentioned Vjpeg).

The Twingly screensaver is a free screensaver that displays blog postings visually on a representation of the globe in real time as they are published on the internet.

Greased Lightbox is a free Firefox/GreaseMonkey script that delivers "Lightbox" type image viewing style (seen on sites like this one) to many sites that link to images such as Flickr and Google images.

PicPick is a free screen capture utility which offers an integrated image editor and various tiny tools such as a color picker, pixel ruler, protractor, crosshair, whiteboard etc.

Click on a world map to see images from all over the world using Earth Album, a free web service that is a mash-up of Flick and Google Maps.

RIOT is a free program which can best be described as an "image size reduction" toolkit. It allows you to reduce the size of your image(s) while previewing a side-by-side before and after. It also delivers a number of handy image tweaking, conversion, and editing tools.

Sysygy is a free virtual 3D art gallery. It allows you to create and use sets of your images and photos in a 3D-rendered environment viewed from a first-person perspective.

Photology is a free image management program designed to navigate large image libraries and find images without the need for tagging or for organizing by folder structure. Instead, Photology scans all images and applies a number of innovative filters such as faces, color, location, time of day, exposure, etc. to find results.

Snapact is a free, stylish image viewing and management software that offers a good range of image manipulation and management functions, including tag and metadata editing, a drop basket, and the creation of virtual albums which can be uploaded and shared using the free online Snapact photo sharing service.

Microsoft Image Composite Editor is an advanced, free program that can combine overlapping images from a single scene or location into a larger, high-resolution panorama that incorporates all constituent images. Output images can be exported into a wide variety of formats including tiled formats like HD View and Silverlight Deep Zoom.

Desktop Takeover is a free program that can place images on your desktop wallpaper either as individual images or "channels" of images that refer to a combination of pre-set list of images, folder(s), or URLs. Channels and background wallpapers can be individually set to rotate/shuffle at a user defined time interval.

Window Ruler is a free on-screen measurement "ruler" tool that offers a number of interesting features, including portability, the ability to "snap-to" any on-screen object, and the ability to automatically resize to a number of common predefined size profiles.