Google has always attempted to collect an extraordinary amount of data about users (and webmasters in particular) - a few recent examples have spotlighted this trend. From what I can tell, there's virtually no limit to the amount of personal data the search giant could collect:

From Google's Search Box

• Every keyword search you perform
• Any websites in the results you visit
• The amount of time you spend on sites before returning to Google
• Common patterns of navigation via search

From Google's Other Public Services

• Locations/Directions you plot on Google Maps
• Messages you send and receive via Gmail or Talk
• Documents you create/edit on Google Docs
• Calendar information you add to Google Calendar
• Sites you subscribe to or click on at Google's Personalized Homepage

From Google's Webmaster Tools

• Any websites you control or have access to via Google Checkout, Google AdSense, Google AdWords, Google Analytics, Google Sitemaps & Google's Embeddable Site Search
• Accounts you create or information you post to Blogger, Groups, AdSense/AdWords, Picasa

From Google's Apps

• Anything you do on your computer after installing Google Desktop or Web Accelerator
• Sites you visit and what you do on the web using their built-in toolbar or the auto-embedded Firefox plug-in

From Google's Web Initatives

• Complete browsing habits of users connecting via free wifi in Mountain View
• Complete browsing habits of users on Google's connections in colleges, airports or cities
• Domain registration data and relationships between websites around the world

At this point, it's not that far-fetched for a black-hat affiliate marketer to be putting on the tinfoil hat everytime the get on the web. I certainly know more than one who connect through proxies, never use the same password/name/address/phone number/credit card twice and maintain that any Google actions against their networks are the result of "data leakage."

The broader question here is - where would Google draw the line? Once they have access to every piece of data about your online activity, from the sites you own to those you visit to where you live, who you email and what you like to do on the weekends, will they build associative databases to help correlate? Is there a "Rand Fishkin" file at Google that a curious engineer could pull up if ever they wanted to research my activities? If so... just FYI - that whole string of searches regarding "smelly pirate hookers" isn't what you think.

p.s. I mistakenly did not write "could collect" and thus made it sound as if Google already tracked all of this information. I have no source to suggest that this is the case, and this post is merely about uncovering the possibilities for data collection, not actualities. Sorry for any confusion.