It's a perennial problem that authors of free software get little feedback from users. Here's an idea: add "I like this program" and "I don't like this program" buttons to Help/About dialogs. They would send some kind of anonymous signal to the author, probably by making an HTTP call to some server somewhere.
This is not a "call home" functionality, which is questionable in many ways. It's completely opt-in, and it's pretty clear to the user what's going on.
Elessar, a simple like/dislike is, well, simple. Having to read a lot of textual feed back would eat up a fair bit of development time. Anyone who wants to provide thoughtful feedback already has the addresses to do so in the About dialog.
Bob, the Debian popcon is per-host, not per-user, which is an important distinction. It also gathers information to Debian rather than sending it directly to the developers of the software. This is also an important distinction. There's no need for Debian to act as a middleman here. In my opinion, of course.
Lars, how many users really use shared systems so much they're going to start rating packages? The host/user distinction seems mostly irrelevant to me.
I don't see much use of this in debian; popcon already says how much packages are used, project websites allow some feedback, and bug reports allow some feedback (though I don't know how many users report wishlist items — maybe only consistent users).
What I'd like to see is more are library rating systems (how many projects, including private closed-source ones, use a library?).
This is about the people who make the software getting feedback. Debian already has popcon, which is an inadequate feedback mechanism for Debian. Not upstream.
popcon also doesn't provide an answer to the question "are there people who like this software" as opposed to "how many people happen to have this software installed".