I think this question is cool to think about and try to answer: What is the lowest integer that doesn't have any hits on google? Is there any reasoning that can help estimating the approximate magnitude it should be?
A problem might be that as soon as you discover that number, you can't tell anyone on the web about it. This for example has no results as of now: http://google.com/search?q=813115181452319
You could look at the hits returned on increasing numbers (eg, 1111 v 11111). A quick glance shows they seem to reduce towards zero by the time you reach 12 digits.
From there, it's probably trial and error - start with 12 1's in a row and fiddle with them. Even try deleting 2 random digits to see what happens (from 12 ->10 as anything with 11 numbers returns a UPS Package Tracking Link / Ad for me). Lowest I had is 111232111222 - perhaps someone should write a Wikipedia page on it?
The interesting number paradox was great, didn't know about it. Almost the same contradiction exists in my problem statement, as someone mentioned below. Would you be able to identify the lowest non-indexed number you probably couldn't keep it from being published on the web.