ImageJoiner allows multiple image files to be joined together. Specifically, it allows users of Windows XP with multiple monitors to have a different background image on each monitor.
To be completed...
ImageJoiner is currently provided free of charge, and I have no immediate plans to change this. No guarantee is given regarding its suitability for any particular purpose, and no liability is accepted for anything that it does. However, I believe it to be safe to use, and I've found it very useful personally!