Mosaic.exe is a free command line tool to create a mosaic of one image consisting of many smaller images.
A folder of small images is used to tile any given input image (see diagram)

Example mosaics created using this tool are shown here
The technique requires a large of number of small images. A small selection of tile images is provided in the ''mosaic.zip'' file below. However it is more fun to create personal tile images. This can be achieved by downloading the ''cropper.exe'' tool.
Both mosaic.exe and cropper.exe are written in C++ using the VXL imaging libraries.
Windows:-
Linux:-
For more downloads see my download page