I define useless feedback as people telling me that they want some obscure feature which I then implement and then, predictably, no one, not even the requester ever uses at all.

I think the problem there is that you aren't understanding what they're asking for. I'm sure they are being perfectly clear in telling you what they want but something weird happens when users describe features and wish lists. They often don't know what they want. Finding that out is YOUR job.

IMHO, what you need to do is ask them what would make it better and then dig in to find out what they really mean. Why do they need that feature? There's no script or formula to do this, but that's one question I've found to be useful.

For example, User A says: put a link on my profile, which when clicked shows my age, sex and location.

You should ask, "why do you need that?"

The User will often respond in some way which will give you a clue as to what they're really looking for.

So, the response to that question might be, "oh, well, people always email me to ask me what my a/s/l is and I'm tired of telling them."

So, using this (very lame!) example, they're not looking for a link - they're looking for a way to show their a/s/l on their profile. You can give them what they really want, not what they're asking for.

I hope this makes sense.

You shouldn't blindly implement features just because your users are telling you to do so. While it is important to listen and react to your user's concerns, it's also your responsibility to maintain the integrity/consistency of the application. Also, if you don't believe that the feature you're building is going to have any effect, then it's already heading towards failure because you're not going to be committed to its success.

I agree with jkush -- if you don't agree with the user, you should engage the user and see if you can get the feature to a common ground that you can agree with.

Also, if your feedback loop is just an email, maybe you should add a forum to make the loop more interactive.

"engage the user and see if you can get the feature to a common ground"

Yes, this is what I'm asking. In direct marketing for example, there are ways that success can be scientifically measured. I am wondering if any of you have used more methodical approaches to improving applications -- or if it's just guess and find out if it worked 2 months from now.

The reason for this is that I just don't always trust users to think deeply enough of the problem for them to know what they want.

A great thing to do is invite your target users to try the app/service in your presence.

But don't lead them or demo anything; just watch how they start, and what they react to/don't understand.

We had a similar experience recently -- http://blog.seeksift.com/2007/03/02/an-epiphany/ -- and it did wonders for our usability.

Seeksift looks cool. I was a little frusterated though when I clicked on the blog and then couldn't find a way to click back to seeksift easily.

Thanks; let me know if you use it and what you think: good, bad, or ugly (actually, especially if it's either of the latter two categories, because that's how we improve).

Thanks, too, for bringing up the point about the blog; there are probably ways of customizing the header to point to SeekSift.com but I got a little frustrated with Wordpress after I found out you can't change their favicon.