Howie's Quick Screen Capture is a simple application that allows you to capture the entire screen or just an active window. Unfortunately, these are the only two capture options it offers and it doesn't include an editor for you to edit your pictures with. You can specify the path where you want to save your pictures and their filename template, file format and bit depth options for all your pictures. Fortunately, the program supports several output formats such as bmp, png, tiff, and jpeg (with lots of quality levels to choose from).
You can also customize the hotkey for captures. The program also allows you to set a timer, so that it will take screenshots automatically, which is a feature not present in many similar programs. What is more, the user interface is very intuitive and easy to use; it's not very attractive, however, since it looks rather old.
In short, Howie's Quick Screen Capture is a free tool for taking screenshots that may only work for you if you take simple screenshots, since it lacks many important features that you will surely find in other free similar programs.