Irfanview

Website: www.irfanview.com
Not free for commercial use

This is not open source, but is free for non-comercial use. Irfanview is a graphics viewer and editor that is quick, will handle any format of file, and will allow you to do most editing functions.

The nice thing about this package is that it just does it. It loads fast, reads and writes loads of formats, even favicons! You can use it to resize and crop images, so it is ideal for touching up digital photos before e-mailing them to friends.

If you need to use it for commercial use, the licence is only $12 or EUR 10 (correct at December 2006). For latest information, see their site.