Links: Shows your favorite sites you have visited.
Docs: Shows and launches your Documents directory instead of going through and it also shows how many files are inside in each one.
Apps: Launches your favorite programs you have launched several times. You can edit them as long as you want.
Pics: Shows your local [or removable (if you have a flash drive)] photo directory, and also launches your preferred on-line photo-sharing sites.
Song: Shows your local [or removable (if you have a flash drive)] music directory, and also shows your title of your song and artist (iTunes required).
Net: The so-called your internet browser launcher of choice.
Date: Your time (24-hour format), day, date, month, and year.
Sys: System statistics: Shows your current status on your screen (e.g. your uptime, CPU, RAM, Free space on your hard drive or SSD, your SWAP, and your i/o internet connections. And also shows your recommended programs for system utilities (some software is recommended to launch them to do so).
Today: It's your virtual newspaper, once you wake up and log in, you'll have your today's weather forecast and your on-line news to help you to stay informed for a little bit. It also shows you the analog time and your current day.
Those icons came from ~VClouds, used in the Weather app from my skin.