Cool desktop modifications

I was checking the may desktop thread in the pictures section, I noticed that there are a ton of people who have cool icons for their HD and other nice little additions to their desktops. I'm assuming that those are mostly done with 2nd party software and I'd like to know what most people use for that.

Any links and/or tips are appreciated. I've only been on Macs for a year now and consider myself a very uneducated mac user so I need help.

SLC