As I mentioned on my Photography page, I use several tools when I work with pictures on my computer. This page is intended to explain why I use those particular programs, and hopefully you find some good ones you have not heard about before.
Adobe Photoshop is the standard for professional photo editing. For the longest time (until perhaps the fall of 2015) I used Photoshop CS2. I then moved up to CS6 and in the summer of 2016 I switched to Photoshop CC (Creative Cloud). This is my preferred tool for photo editing.
The GNU Image Manipulation Program (more known as GIMP) is a free alternative to Photoshop. It does not have all the functions, but it is pretty close. The functions are organized differently from Photoshop, so if you are used to Photoshop it will take a while to find everything. As with most free software, it is easy to tell that they been developed by programmers, they lack the polished user interface found in most commercial software.
However, if you are used to Photoshop, GIMPshop is a modification of GIMP that is intended to emulate the feel of Photoshop. Just like GIMP, it is available for Windows, MacOS and Linux, while Photoshop is only available for Windows and MacOS.
Cam2PC have not been maintained or updated since 2007, but it is still the best program I found to transfer images from my camera to the PC. It is simple to use and have all the functions I need. When I download my pictures, they get automatically sorted into different folders, by date the picture was taken. So if I have pictures from five different days, they get sorted into five different folders. When downloading the pictures I can also enter a keyword or short description to be added to the folder name.
The program let me browse pictures in an easy way, very similar to Windows Explorer. Pictures can be resized, cropped, the format changed, and even simple modifications like adjusting colors, sharpen the image or remove red eyes. It also let me select pictures (from different folders) into an album. This album kan be printed, burned on a CD/DVD (if you have Nero installed) or made into a slideshow or web gallery, the latter can even be automatically uploaded to your web server. The program is $20/€15 and I consider that well worth it.
In Ubuntu, a Linux distribution I use, a program called F-Spot is included. I have not been using that program very much. F-Spot load the pictures into a database, which takes a long time for me when I have 120GB in about 64,000 pictures. It is also harder to get an overview of the pictures. I prefer the way Cam2PC handles it, let me browse them directly in the file system. However, F-Spot has a function to identify duplicates, which Cam2PC lack.
AutoStitch is a really cool little program. It is free, and it let you combine a number of pictures into a panorama. Just take pictures and make sure they overlap about 20%. Then load them into AutoStich and let it do it's magic. The code is also used in several professional tools, like AutoPano.