|About as productive and organized as a hungover teenager at Taco Bell.|
That being said, the obvious first choice is Rainmeter. This is an open source software that allows your desktop to be customized with low-memory hogging applications and "skins"--from your typical clock to weather to even RSS feeds and email notifications. Rainmeter is the basic skeleton that you'll need to install to do anything with your desktop. There are a few other options out there but in my opinion, Rainmeter has the most versatility and technical support. It also allows budding developers and software designers to give its source code a whirl and create apps/skins of their own.
|A very basic Rainmeter desktop--this is the Enigma set of skins, I believe.|
As you can probably see, Rainmeter focuses not only on design and art but functionality. Imagine never having to use your Start menu again, if possible. You can easily link any program on your computer to a small icon or bar here on your desktop. It makes for a world of efficiency.
Rainmeter is a fantastic start and all, but what if you're not one for the amount of work it takes to set up a beautiful desktop? Well, luckily, if you have RM installed, you can hop on over to either the Rainmeter forums or DeviantArt--Rainmeter to find many skins, addons, and even full fledged desktops for your perusal.
|A typical user-created screenshot of their desktop, using RM and other tools.|
|My current desktop, courtesy of DeviantArt's Tatenokai.|
To get the above desktop, make sure you have Rainmeter installed and then navigate over to Tatenokai's Newspaper Desktop on DeviantArt.
Best of luck on your customizing endeavors. As always, you should thoroughly read Rainmeter's instructions before you set out--lest you destroy your desktop beyond all repair. Just kidding!