Photoscape - high quality photo editing software, that enables you to fix and enhance photos.
PixBuilder - Free Photo Editing Software for PC
FastStone Image Viewer - FastStone Image Viewer is a fast, stable, user-friendly image browser, converter and editor.
PhotoDemon - Lightweight portable BSD licensed photo editor for Windows focused on performance and usability.
IrfanView - IrfanView ... one of the most popular viewers worldwide.
Fotografix - In addition to being totally portable, Fotografix has a ridiculously small footprint.