Andrea Mosaic is a useful and fun tool, completely free, that lets you create your own mosaics from photos, known by the name of Photomosaics. To work with Andrea Mosaic just choose a photo you want to work with, and then select a photo album to place your mosaics in.
The Andrea Mosaic interface is very simple to follow; from it you can create and modify the photomosaic, adjust the colour, rotate, select each piece of the mosaic, etc. Andrea Mosaic is a program that experimental users, or those who are using it for the first time, will like.