Here is a site full of amazingly useful material - http://www.in-terre-actif.com/fr/index.php. Ideal for work related to Citizenship, Geography and Science. Includes ready-made Powerpoint slides about climate change, what people eat in different countries of the world, and loads more.
A great French website about slavery in Martinique, with an interactive game that teaches about the history of slavery - http://www.esclavage-martinique.com/
(With thanks to Marie-France Perkins)
Please add useful links to other websites (just click on Edit in the tab above). Here are some to get things started:
Resources from Elliott School in London (with thanks to Neil Jones and his colleagues at Elliott):
A US website about French immersion teaching with lots of resources
Science Across the World - a great way to share findings on science-related themes with pupils across the world
www.dailymotion.com - a fantastic source of video clips in a range of languages, including themes such as Fair Trade and other current affairs topics.
http://www.bbc.co.uk/learningzone/clips/ - BBC learning zone broadband 'Class Clips'. A great search facility allows you to find video clips tagged for primary and secondary topics. e.g.try out French / food.