The real power of the tool is in its ability to capture large numbers of Web pages at a time. By feeding the program a text file with a URL list, the program can fetch and generate page screenshots for each of those URLs, dumping the images to a location of your choosing, using a naming convention you can customize to your needs. Web designers who want to map out a blueprint for an entire site, for instance, might use these kinds of screenshots to visualize the flow of links on multiple pages. You can even instruct the program to crop an image beyond a certain size, or create images from browser views set to a specific width and/or height.
The free version runs in both the command line and GUI mode, and outputs whole webpages as JPEG files. If you plan to use the product to take large numbers of these kinds of screenshots, and wish to customize specs like a maximum width or an image file format other than JPEG, a $55 "Personal Edition" offers these and other features. For commercial users, a $110 version that runs on a server adds additional power and flexibility. But unless you have the kinds of specialized needs that the paid versions demand, the free demo version should suit yout needs.
Note: If you're using Windows 2000, you will need to install gdiplus.dll from the GDI+ Platform SDK Redistributable (Windows 2000 users only) to use this program.