Create Panoramas with Hugin

Hugin is free open source software for creating panoramas from a series of photos. It is not terribly difficult to use, but you should follow one of the tutorials such as the Lifehacker Hugin tutorial. This explains how to set control points between photos in order for Hugin to know where things line up.

There are downloads for Windows, Mac, and various flavors of Linux. For simplicity, download from the pre-compiled versions.