Just wanted to quickly introduce to this community Zemanta plugin. It extends your writing interface with suggestions regarding the things you write. It will suggest hyperlinks (Wikipedia, IMDB, Amazon, ..), creative commons images (Flickr, Wikimedia Commons, ..), related articles from blogosphere and tags.
You can grab free WP-MU plugin version from - http://wordpress.org/extend/plugins/zemanta/, or take a look at interactive demo at our homepage - zemanta.com
-- Jure Cuhalev, Zemanta