This is freeware
photo editing software that I've come to appreciate very much.
It is easy to use and works quickly and accurately.
I use this software for noise reduction as well as photo editing
when preparing HDR (High Dynamic Range) photos as well as touching up non-HDR photos.
This freely distributed software gives you a variety of image manipulation
I use this for photo retouching--specifically
for perspective transformation, such as in the
image on the right, where the original shot, taken with a wide angle lens, distorted the building:
With this software, you can upload or download files to and from many photo-sharing sites through one interface, including flickr and picasa.google.com.
It is invaluable because it is fast, easy, and allows you to upload images
in larger sizes.