NOTE: This script requires drush 5.x
The script downloads the current top 100 drupal modules from http://drupal.org/project/usage It requires drush: http://drupal.org/project/drush And the BeautifulSoup Library: http://www.crummy.com/software/BeautifulSoup/bs4/doc/
The BeautifulSoup library is packaged with this program, so you don't need to download it unless you want to.
Check out the Downloads for an OS X app that downloads all of the modules within the application package contents.
After you double-click the application, use finder to "Show Package Contents". Within this folder open Contents/Resources you will find a folder called drupal-modules. This is where the downloaded modules are.
After you install drush, from the command line type:
python drupal-top-100-download.py