I strongly recommend this excellent post from Justin Kan: http://justinkan.com/the-founders-guide-to-selling-your-comp...
I... don't know? I know at the low end, you are completely correct. If I had a nickle every time someone wanted to buy prgmr.com for the ebay value of the servers, well, I'd be able to buy another server or two.
I ended up being pretty free with my revenue numbers... and yeah, most people are just sniffing. I guess I wasn't much of a business person, so i didn't really understand (still don't, really) why those should be super secret.
But on the high end, I would assume (and again, zero experience on the high end) I would assume that if it were worth google's lawyer time to set up the deal that they would come out with a price that was, you know, significant money by my own standards.
Consider the following: how would you value a business, if you don't know how it is structured, how it operates, and how much revenues and profits it's generating?
I can potentially see that working for some cool technology startup, or an acqui-hire, but not for an actual business with revenues (and more importantly, profits).
Those small acquisitions, they're not investments for Google, they're expenses. The $500m-$1bn+ ones, those are investments. Big difference in thinking.