Stitching scanned images if your originals are too large for your scanner.
DoubleTake is the "nano" of stitching software. Drag & drop your images onto or into DoubleTake, arrange them, and check the overlaps. When you are done - save and perhaps copy and paste the result to iPhoto.
DoubleTake is simple enough to not require a manual, but a few annotated screen shots highlight a few main points.