You can automatically download images from your favorite image board. One of the coolest parts is that you can automatically set this program to watch your favorite threads so that whenever a new image of your interest is posted, your computer will automatically download the image so that you can view at your convenience. You won't have to sit and wait around to see the content you like, instead you can rely on the program to passively save the best content so that you can view it at a later time.
This free and open source program is a great choice if you happen to be one of the many people that uses a Chan style imageboard site. It's easy to use and can be customized to your satisfaction, and you can rely on it to catch all the images you are interested in so that you don't have to spend every second parsing for the best images. It will allow you to quickly build up a great library of images that can be used for any number of purposes.
Works on Windows, Linux, and Mac computers.
It is a free program with support from the developer and the community. Because it is built in Qt/C++, it can be run on any operating system and has very minimal requirements to run smoothly.