The Google blog notes how huge the web is now, with Google indexing over a trillion unique URLs. As they note in the article the actual number of indexable URLs is, in one sense, infinite. For example calendar pages will automatically appear as you scroll through many applications, continuing through the years until..the singularity and beyond. Of course Google does not index many of these “empty” URLs or even a lot of junk or redundant content, so the true number of real, unique URLs is actually well above a Trillion.
I think a fun question is this: What will the information landscape look like in, say, 20 years when we should have the ability to pour *everything* from the past and the present online? Questions might take a different form if we had access to every reference on a topic that has ever been produced. Algorithms will be used to sort through the oceans of content much as Google does now, but with far more precision and better comprehension of the whole mess.