As the 360 MacDev conference continued in Denver today, the attendees had a chance to stuff their faces with apple pie courtesy of a vendor, and then sat down to here a talk by Josh Abernathy of Maybe Apps on the mechanics of good UI design. Josh started by making a distinction between graphic design (making something pretty) and interaction design (making something that is a joy to use).
Abernathy was primarily focused on the graphic design of applications. He suggested that many developers hire a graphic designer to do this job, as programmers aren't necessarily good designers. Pixie, a UI "explorer" that is included in the Apple Developer Tools, was noted as a simple and useful assistant for seeing the closeup details of how other developers have achieved a certain effect.
Keeping a scrapbook of good designs is another hint that Abernathy brought up. He wasn't advocating stealing user interface elements -- something that several developers I talked with at lunch have had to put up with during the last few weeks -- but instead to use those elements as an inspiration for future designs. Abernathy suggested visiting Flyosity.com and 365psd.com for excellent hints on how to use graphic tools like Photoshop in designing user interfaces.