I have been playing around with http://wolframalpha.com lately and it has a lot of power behind it. I mostly use it for doing math stuff when I don't have a calculator in front of me and it can even do some stuff I cant do on my ti-89 like Laplace transforms. When it returns a result it often time gives a comparison of other things that have the same unit. As an example, I asked it about 15 gigs and it immediately figured out what I was talking about and told me how big that was in relation to a blueray disk,60%, as well as how long it would download at different speeds. All this information got me thinking about what kind of questions it can answer and what it cant. The questions it cant answer fall into 3 main categories and while I could never list all the things it can answer I can easily list what kind of questions I want it to answer.
"average size of an iphone app in the apple app store" - while this query would take a lot of work to acquire the requisite data I think it could be ...