The Demo Site

1. Aller [Download]
2. Aurulent Sans [Download]
3. Bitstream Vera Sans [Download]
4. Colaborate [Download]
5. Fontin [Download]
6. Luxi Sans [Download]
7. Mayberry Pro [Download]
8. Museo Sans [Download]
9. Sansation [Download]
10. Surface [Download]

Source : http://www.myinkblog.com/2009/04/19/10-awesome-free-sans-serif-fonts/