See real-time data on a host of topics important to daily life around the world:

• world population (e.g., births this year, deaths today, net population growth for today)
• government and economics (daily government spending by category; computers sold)
• society and media (new book titles published, money spent on video games, Google searches)
• environment (forest loss, carbon dioxide emissions, current average temperature)
• food (tons of food produced; people who died of hunger)
• water (water consumed, people with no access to safe drinking water)
• energy (solar energy striking Earth; oil pumped; oil, gas, and coal left)
• health (deaths caused by alcohol, suicides, road traffic accident fatalities)

Worldometers' algorithm takes the latest statistical data available from the United Nations (UN), the World Health Organization (WHO), the Food and Agriculture Organization (FAO), and other institutions, and then processes them together with its estimated progression to compute figures current up to the millisecond.

Available in dozens of languages, this site is part of the Real Time Statistics Project. Read more about that here:

http://www.realtimestatistics.org/

Maths online also provides selected online tools, including scientific calculators; tools for plotting 2D and 3D graphs, differentiating and integrating functions, and solving equations; and links to other useful collections of tools:

http://www.univie.ac.at/future.media/moe/onlinewerkzeuge.html

The site also lists and describes math links that emphasize interactive learning material.

http://www.univie.ac.at/future.media/moe/einzelthemen.html

http://tierneylab.blogs.nytimes.com/tag/puzzles/

John Tierney, The New York Times' science columnist, writes challenging word problems that "put ideas in science to the test." Solve and comment on the puzzles and their extra credit extensions.

See also Tierney's blog entries on mathematics:

http://tierneylab.blogs.nytimes.com/tag/mathematics/