Recently, I came across some “desktop artists” and I too wanted to delve into this art. I found out the app being used was a FREE tool called Geek Tool (that I used years ago but really never really figured out). I’m learning it now, but still it’s a bit difficult unless you know a lot about scripts. I do not know any scripting language but I do know how to search on YouTube and Google! And well… if you can read and follow along with videos, you too can have an active desktop like I now do thanks to scripts.
First off, I downloaded GeekTool and it installs as a System Preference. From there it’s drag and drop. You drag a shell, image or file to your desktop and code away. I have found some places that have tons of scripts (bash). If you have a script, all you have to do for most of them is drag and drop as seen in the image below.
Some of the scripts just work. You don’t have to do anything. Then there are others that need some tweaking and that’s where YouTube comes in handy. Search for “geektool scripts” or “geektool for dummies.” Whatever it is you would like to be seen on your desktop for the most part can be seen. From RSS feeds, to e-mail, to your local weather forecast (as displayed on my desktop).
I have included some more links as displaying the weather and whatnot is a bit cumbersome. So these links will explain better than I can.
This is my finished product, finished to a point cause I change it daily to my liking 
P.S. As you can see I also changed my dock and menubar. I have included those links as well. I love the way my desktop looks now. I wish it was built-in, instead of having to change system files like I had to do. Oh Well. 
NOTE: BE VERY CAREFUL and MAKE BACKUPS OF ALL FILES!
Links:
Black Menubar and Black Dock Mods
RON: A geek who works in the Graphic Design field and currently lives in Pittsburgh, PA. He is the primary site designer for Geek Trio. He has also been writing software reviews for several years. Ron brings his sense of humor and a unique viewpoint to the podcast. 
Now THAT is cool! Nice work Ron.
Thanks! I like changing my desktop. Love the icons and designing a desktop. It’s fun! I was thinking about changing the overall OS. But I’m just gonna leave it be…
Some of the desktops that other people did are amazing. One dude made his look a trolley map. Each trolley stop was an alias for an application but represented as a “dot” like you’d see on a map.
The trolley map one. Sooooo cool:
http://www.flickr.com/photos/aogu/5160001702/in/pool-87689304@N00/