I was lucky enough to attend a week-long Human Factors International session on usability a few years ago*. As a developer with a long term interest in getting to the human root cause of so many programming problems, I loved it. One of the freebies from the course was this button:

It's excellent advice. I still have this button clipped to my mug boss to periodically remind me that, no matter how cool the feature may be, if users can't find it – or understand it – you're wasting your time. So make sure you have your priorities in order before you start: usability first, feature second.

Jensen Harris provided a striking example of this phenomenon in action today:

One of the most startling and consistent pieces of feedback we've received from the early deployments of Office 2007 Beta 1 has been: "It's great that you added the drawing tools to all of the Office programs! Now I don't need to create the drawings in PowerPoint and copy them into Word/Excel/Outlook..."

Surprised? I certainly was.

While the drawing and graphics engine has certainly been massively improved in Office 2007, the same basic drawing capabilities have been available in Word/Excel/PowerPoint since Office 97. Yet, again and again we hear stories about people assiduously creating drawings in PowerPoint and copying them over piece by piece into their Word or Excel document. I remember during a site visit watching a man create a simple flowchart in Excel which should have taken 3 minutes actually take 15 minutes because of all of the cross-application, clipboard, and windowing work it took to keep moving shapes between the apps.

When is a ten year old feature suddenly a "new" feature? When users can actually find it!

* HFI also has a great technical reference section on their site, which includes the archives of their UI Design Newsletter back to 1998. It's worth checking out if you haven't done so already.