How to get the effect?

how to do this effect? http://drupal.org/files/d7-contributor-cloud-huge.png.(http://yurik86.deviantart.com/art/2011-Typographic-wallpaper-RGB-181622402?q=boost:popular+2011+wallpaper&qo=1) what way of all the words are put on the image ? which design tool can do a image like that effect?

These aren’t automated, but manual labour. The artwork starts with a background layer, followed by the word or shape you want (Drupal’s logo shape or 2011 in the case above). When you have placed your shape or word above the background layer, start adding and arranging your type accordingly. It’s quite a labour-intense undertaking.

oh,it’s a too complicate work.