ColorZilla is s a very useful add-on for Firefox that enables you to get the color code for any point in the browser window. You can then quickly adjust this color and paste it into another program. It also enables you to zoom web pages and measure distances between any two points on the page. Homepage:... 

  Resizor is a new free software for high-quality image resizing and re-targeting. It uses new image re-targeting technique called seam carving. You ca red more about it at wikipedia. This technique gives great results and it is not even implemented in popular commercial products like Photoshop... 

  PhotoRazor is simple photo tools that enables you to resize your images. It is very easy to use. You  can convert  whole folder of images with just one click. Original images are untouched and resized images are saved to a new folder.   Homepage: http://www.stormdance.net   Read More →

  Greenfish Painter is very interesting painting and image editing tool. It allows you to paint with a virtual brushes, calligraphic pen, charcoal, or chalk. Painter provides you with a virtual canvas to imitate real painting so results will look more like a real painting. it comes with variety... 

The GIMP is also available as a portable app. It can be run entirely from a removable drive. http://sourceforge.net/projects/portablegimp   Read More →

TechZilo made a nice list of 40+ top GIMP plug-ins. Most of them are for web design or photo manipulation. Take a look at the list.  Read More →