I'm a little frustrated with WolframAlpha. My experience (and I have been trying to use it ever since it launched) is that it's fine for playing around whilst modifying known working expressions, but that it is incredibly opaque whenever I want to use it with a "real world" problem.
As an example, today's xkcd has a picture of a signpost indicating 115 miles to Jackson and 98 miles to Memphis. I thought it would be fun to try and identify where this sign post actually was, and WolframAlpha seems like the perfect tool to do so. But I just can't get it to even ask the question. I've tried formulating the question in plain English, but it doesn't understand, and I don't know how to represent things like "distance" or "Jackson, Mississippi" in pure mathematical code. This is typical of my experience with WA.
So, how do I express my question such that WA understands? And where can I get some decent documentation that would allow me to figure this out for myself?