You can find a few examples of Metapixel mosaics in my Flickr Mosaics set.
All the examples on this page use the following image of my juggling partner Tini and myself (scaled 2048x2048) as the source image:
All images below were generated by using the same set of nearly 21000 constituent images.
This image is a classical photomosaic using the subpixel metric with global search:
This is a classical photomosaic using the wavelet metric with local search with distance set to 8 and cheating set to 30%:
This is a classical photomosaic using the subpixel metric with global search and weights of the I and Q channel set to 0, i.e. weighting only luminocity:
This image is a collage photomosaic using the subpixel metric with defaults weights and a minimum distance of 256 pixels:
