New features of Google Reader (see Google Reader: Now with More Social! ) allow you to identify target audiences by what they already like or favor:

” …. And in a move that looks a heck of a lot like Facebook, Google Reader also add the “like” button to the bottom menu of its stories:

Here’s how it works – you take strong content that has a known audience such as Paul Krugman‘s OP-ED and posts at the New York Times.

1. Most readers of Paul Krugman are probably democrats
2. The same readers who favor Paul Krugman think the 2009 Stimulus Package is inadaquate for the country’s needs.
3. Most readers of Krugman think the previous administration were crooks.

With those three points in mind we can look at Paul Krugman’s recent posts and find out who likes them.

It would help if Google Reader had a sorting by the number of “most liked” posts in a category, but it doesn’t yet.

However, as the “like” button was just added recently AND does not appear on all mobile applications of Google Reader (like the iPhone, where I do most of my Google Reader reading) there’s a lot of information that’s not being collected yet.  In time, say over the next year, I believe we’ll get to 60-70% of all those reading RSS feeds in Google Reader to have their likes recorded – but right now, that’s not the case.

Once you have settled on the content, in his case, Paul Krugman, just  go through every Paul Krugman post, get all the names, de-duplicate, and then look at the articles each have read.

At this point, the process would me manual, but I’d imagine, tools could be written to do this much faster.

The last part is most important – you can carefully contact people in you “list” for persmission – but here’s at least, a way to build a list based on what some actually likes.

Once you build a list, gradually, maybe spending 15-20 hours on it – and you can come up with 400-500 profiles to contact while looking at the details of what they “liked” will confirm your choices.  You’ll still need to figure out the best way to contact other readers – probably by first following them in Google Reader – go look at their public Google Profile and then request to contact them.

In a way, Facebook could have done the same thing – but they haven’t, as far as I can tell.

It’s all in how it’s done – weather it violates privacy or not is how people are contacted and if they are giving their permission to have a dialog – if they haven’t then it a violation of privacy – but if they have, then you can approach – with this new “house list”.