Browsing one of my reference sites, macrumors.com found a stylish, interesting way to increase keyword density, without crowding in excess your site. Looks this way:

20140407-seo-footer-keywords-density-improve-at-macrumors-site

Placing that descriptive text at footer, makes completely sense, and its a must for SEO. I’ll try to use it on my projects. As and added value, helps a lot to give sense and balance the visuals from footer elements.