Post a review of a book or other product on Amazon.com, and the information may find its way into the company's file on you. CNET has more on Amazon having been granted a patent for a system that gathers clues from reviews about customers' gift-giving habits in order to suggest future gifts and reminders.

Consumer advocates worry that the company's profiling practices may have gone too far and could exploit the giving of gifts and the sense of community that customer reviews were designed to engender.

Here's how the proposed system works, according to Amazon's patent claim: Amazon would gather information about gift recipients, including their names, addresses and items customers send them. The system would then try to guess their gender, age and the gift-giving occasion based on the type of present, messages written in gift cards, dates gifts are ordered, items on wish lists, and commentary in related consumer reviews.

The system appears particularly geared toward people buying gifts for children, with its ability to recommend "age appropriate" gifts.

Jason Catlett, founder of Junkbusters, a consumer watchdog, said:

They are building a speculative profile on you before you even know you're dealing with them, because someone sends you a gift.

He's particularly dismayed by the prospect of Amazon monitoring customer reviews for marketing purposes.

Well, so am I. But I think Catlett is onto something when he says:

People will hesitate to publish reviews if they know the result is to enlarge their profile in some secret marketing database.