The Firefox extension Abduction makes it easy to do webpage screenshots. This extension for Firefox has the potential to be a website designer’s best friend. Being able to do quick and easy screenshots can make any type of website design work easier. You could cut minutes out of building that online portfolio or whatever other projects you might have.
Here is a little more about the Abduction add-on from the developers:
Right click on any web page, frame or iframe, click “Save Page As Image…” and then resize the selection around the piece you want to save. The element that you right clicked on will automatically be selected, you can quickly expand the selection to the entire page by double clicking, to restore, double click again. This add-on is entirely open source, contributions are welcome at the github.
You can download Abduction from the Firefox add-ons website.