Here's a nice and free customization icon I've just started using:
Desktop VisualizeR - Android app on AppBrain
Since I've been using AppBrain instead of the Android Market, Plume instead of Twitter, and now either Miren or Dolphin Mini instead of the stock browser, I've had to look at the app-specific icons instead of the function-based icons that Android came with. No more!
Desktop VisualizeR allows you to customize the icon with your shortcut, and it even allows you to use icons from other installed applications. Now AppBrain uses the standard Market icon, Plume uses the standard Twitter icon (it is installed as well), and when I decide on Miren or Dolphin Mini I will set my choice to use the standard internet icon.
It has features beyond that which I have yet to explore. There are other popular apps with the same functions - BetterCut comes to mind - but the nice thing about Desktop VisualizeR is that it's free. If you've ever wanted a little more power to customize your homescreens, definitely check this out.