Wolfram Alpha opens up API, makes it free for personal use
And now, Alpha has gone on to make all of its rich data freely available via a new API for developers. This means it's now easier than ever for developers to query Alpha and pull specific information back into their app for display to their users.
The API returns the result as a bunch of XML, which is very easy to slice and dice. You can either use Alpha's built-in charts and graphs, or just get the numbers and display them as part of your app.
Better yet, the API is free for personal use. I'm not sure what exactly qualifies as "personal use", but that does sound encouraging.
If this piqued your curiosity, you might be happy to know that Wolfram has put together a nice API Explorer. That's what you see in the screenshot: You can just feed it with any query you would feed into the "regular" Web interface, and then analyze the XML it spews out. Now we just have to wait and see what apps developer community comes up with!