It's not clear which, if any, of the Korean music pop "girl groups" were the top one in 2009. Some tried to predict who will dominate and some made compilations of their favorites.

Some of the popular groups (and their songs) as of mid-year are shown in this video below:

This next video from late 2009 shows many of the top Korean "girl groups". These include Girls Generation, SNSD 소녀시대 Kara 카라 2NE1 투에니원. It also showcases the Wonder Girls international touring.

The video is in English, and also is subtitled when necessary.