My students learn about the semantic web in class and the Web 2.0 stuff that lays on top of it. (I honestly don't understand why people insist on making a distinction.) Massive data storehouses and bringing data together from collections with different scales. Mind boggling stuff when you consider the difficulty of creating an extensible ontology that will serve people who are just kids now who will have information needs you can only guess at in order to make connections you never thought of.
Not too long ago I ran into this: Gapminder which is a really cool utility that Hans Rosling presented at TED 2006. The presentation link is on the left at the top of the page.
Rosling is one of the heroes of the semantic web because he is insisting that the UN make its data warehouse open up to the world. If the people at the UN understood what he was talking about, he wouldn't be a hero. But Professor Rosling keeps banging his head against the door and someday they will figure it out with his help.
Sorry about the digression, but you will see why it is important to kids in a minute.
Rosling's work allows you to see a graphic depiction of moving data across a long baseline that elucidates longevity, GNP, family size, and infant mortality as a measurement of overall quality of life. It opens up a new view on Globalization and allows you to see just how provincial our education is.
Now, Google has made the creation of graphic display from LIVE data possible not just for wonks, but for students!
Google Blog article
GoogleFinance focuses just on financial data from Google Finance. Using a similar syntax, you can look up the price of Google stock [=GoogleFinance("GOOG")] or the 52-week high of Apple [=GoogleFinance("AAPL", "HIGH52")]. And since stock prices tend to change more often than, say, the capital of California does, we update them in your spreadsheet automatically. So if you leave your portfolio spreadsheet open, you should see numbers get updated as you would on Google Finance itself. Of course, we also have the same 20-minute delay on financial data.
So as GoogleLookup and Google Finance let you pull data from the web into your spreadsheet, we've also make it easier to put your data back out onto the web by publishing it. If you go to the "Publish" tab at the upper-right of your spreadsheet, you can publish your entire spreadsheet (or just one sheet of it) so that other people can view it as HTML, PDF, or even as an Atom or RSS feed. You can finally share your spreadsheets with others without them having to sign in to their Google Account. And if you go to the "more publishing options" link, you'll find some other cool options (duh!).
This is a killer app for teaching the value of the semantic web.