Update: Fixed as of iTunes 11, which changed the featured item presentation entirely.
This is a minor nit, but one that has been bugging me for years. When you open the iTunes Store, you're greeted with a panel at the top that rotates through some of the featured albums or applications (this is now repeated in the Mac App Store and iPad App Store). The problem I have with it is that it only lets you scroll this list one way. Here's the button they give you to view the next thing (Mac App Store UI pictured here, but it's the same problem):
When you use that button, the thing at the bottom scrolls off and moves to the big panel on the left. Or, if you just sit there, it does that itself after a few seconds. But there is NO WAY TO MAKE IT GO IN REVERSE. So, if your eye catches a glimpse of something you find interesting on the big panel but it swaps out with the next thing before you can click on it, you have to sit there and wait for it to roll around again. Or click-click-click the little down button to get back to it.
Now, Apple could fix this by adding an up button to the top right panel. That seems like a small thing to ask. One teensy extra button? Oh — right. Apple has a thing about extra buttons.