So what do you think? Does this photo-mosaic look ok?

I discovered a cheat way to do a photo-mosaic using photoshop:

1. Place all the tiny photographs on using the 'Place ...' function. Use this as the backrgound without any adjustments.
2. Setup 3 layers of the big image using the blend mode 'Overlay', 'Screen', and 'Mulitply' from the top down.
3. Play around with the Opacity setting of each layer to get the desired effect.

So go and try it! Or if you have any other method feel free to share with me!