Image Eye is a fast - and free - image viewer with a nice clean user interface.

Feature high-lights:
- The only image viewer you need for viewing and browsing images.
- Clean with no unnecessary menus and toolbars wasting your desktop space.
- Uncompromising with the image quality.
- Small and very fast, highly tuned code.
- Reads all common image file formats.
- Easy to rotate, mirror, zoom, pan, and adjust contrast, brightness, sharpness, hue, saturation, gamma, et c.
- Image adjustments can be saved non-destructively and automatically reapplied when you next open the image.
- There's an image index feature with very fast thumbnail-icon creation.
- It does not attempt to be a half-baked editor, format converter, or media player.
- It does include a simple slide show scripting language.
- The user interface has been translated to several languages.
- Freeware!

Features for the tech-nerds:
- Asynchronous file I/O allows decompression to start before file reads finish.
- Speculative decoding caching of images in the background.
- Data parallelism exploitation through the use of SSE2 and SSSE3 SIMD vector-instructions
- Task parallelism exploitation through extensive multi-core support.
- Hand tuned code optimizations for critical paths in assembly code or using compiler intrinsics.
- High quality resampling (image resizing) using Catmull-Rom interpolation.
- Extensive text meta support.