Links to sister projects are located at only the left sidebar. However, I think having logos and more visible links to other projects on the site's main page would benefit many readers. Wikimedia Commons has logos of those projects on its main page|. Why not have MediaWiki.org done the same?
Topic on Project:Village Pump
I think linking from the main page to the Wikimedia content projects would be rather pointless. This wiki isn't a content project, and doesn't serve the same users, unlike Commons (or Wikidata or …).
Agreed to what Jdforrester said