You don't have to put up with the same old boring icons all the time. In fact, if you look around, you'll find there are many sites out there where you can find all sorts of original icon sets to freshen up your desktop.
Take deviantart. One of the most vibrant online communities for artists it showcases all sorts of works, from icon sets to photography, flash or artisan crafts. deviantart is a great place to go and pick up a new screensaver, wallpaper or icon set, as most of the things you find are also completely free and made by extremely talented artists.
You could really spend hours digging around in all the categories that make up deviantart, especially giving that new items are constantly being added. If you're looking for top notch icon sets I recommend taking a look at the selection made by Noupe. The online resource for web developers has built up an impressive list of 40 amazing icon sets.
You'll find many icons specifically for Mac, such as those for the iPhone or for Leopard, but their selection also includes a few sets for Adobe products, with many stunning adaptations of the sober icons that Adobe released with their CS3 series. I also quite liked some of the more original sets like Oxygen, which consists of bubbles covering very minimalistic icons, or the Yoritsuki set of Japanese styled logos. For PC users, I recommend the Windows Icons V1 set, with its rounded, shiny and bright new icons that could actually make a Mac user envy your XP or Vista PC.