Every time you fetch a web page, your browser sends a special User-Agent string to the server telling it what software it's running. It's defined in RFC 2616:

This is for statistical purposes, the tracing of protocol violations, and automated recognition of user agents for the sake of tailoring responses to avoid particular user agent limitations.

Fast forward to 2009, and here's the User-Agent string you get from Google's fancy new Chrome browser: It's like a browser salad! But the Google guys aren't doing anything wrong, this boneheadedness has to be there in order to satisfy the "automated recognition" part of the spec. Chrome's just a little ol' chameleon.

Do you use iGoogle? Do you hate the sidebar on the left side that wastes 100 pixels with useless tabs and an advertisement for Google Talk? There's no official way to turn that sidebar off. But if you set your start page to http://www.google.com/ig?gl=all, why there's your iGoogle page without the sidebar. Lovely.

Don't get me wrong, I love iGoogle. I've been using personalized start pages for years and iGoogle is the best. It loads super fast, it's easy to configure, and it has enough useful modules to keep me occupied. Just don't appreciate some product manager deciding to keep features in front of me that I do not want.

Google has just announced a major new ads product, interest-based advertising. Google is now building a profile of you, the user, based on what websites you go to. They then use that profile to show you ads for things you think you'll be interested in. For the first time Google's targeting ads at who you are, not just what you're currently looking at.

I'm usually quick to criticize Google on privacy issues. But not this time. Because along with this juicy new ad product, they're giving users unprecedented control and visibility into the ads they are shown. We can opt out of tracking entirely. Or we can set our ad preferences, viewing and altering Google's profile of ourselves. And Google has a detailed and readable page describing how their ad products works with personal user data. All of this privacy protection looks real, a user-focussed product, not just some sham to satisify lawyers.

Interest-based advertising will likely be enormously profitable for Google, both because the ads will work better and because no other company has the resources to compete. It's essential for Google to treat user privacy seriously, to protect their ability to implement the product. It's also good for users, both that we have control of our personal data and that we may actually see ads that are interesting to us. And of course it's good for advertisers, too. I think everyone wins.

PS: I used to work at Google, but it was a long time ago. I have no inside information on this ad product.

Following on my new fame for looking at the ages of Craiglist ads, I did a bunch of crunching and got six months of collected ad data into a database. Which makes it easy to produce reports like the following:

There's a 10:1 variance in ad volume based on the hour. The quietest times are 4am with about 15 ads an hour, the busiest times are around 8pm with about 150 ads an hour. Noticeable bump when people get home from work, surprisingly little variation in day of the week. Overall the distribution looks like graphs of pretty much any Internet activity with some bias towards more use in the evenings.

What I really want to get at is the content of the ads, classify them by desired partner, desired scene, drugs, desperation, etc. I need to chat with someone who understands text clustering.