XnView MP - XnView is a free software that allows you to view, resize and edit your images. It supports more than 500 different formats!
GIMP - GIMP is a multiplatform photo manipulation tool.
IrfanView - IrfanView ... one of the most popular viewers worldwide.
Adobe Photoshop - Adobe Photoshop is a webtop application for editing images and photos online.
FastStone Image Viewer - FastStone Image Viewer is a fast, stable, user-friendly image browser, converter and editor.
Pixelmator - Pixelmator is an image-editing application for Mac and iPad.