The icons on the top left called Multimedia, Network, Organization, Games and Tools are provided by the 'Apps Organizer':
This lets you label applications, and then display those labels on your desktop. It's conceptually similar to placing applications into folders, but with the added benefits of automatic sort, custom icons, and the ability to associate multiple labels with an app.
The little green android guy in the center left is a widget provided by the Advanced Task Killer:
I can just tap the icon to kill any apps that I've selected. This is useful for stopping misbehaving apps, or reclaiming resources from the apps I want (vs. what the system determines automatically).
The 'Starred' folder lists a subset of contacts that I've selected (synced to Google Contacts). This gives me quick access to information for folks I regularly contact.
The long strip of buttons at the bottom is provided by Widgetsoid2.x:
This provides a customized selection of functions. I've enabled WiFi on/off, Manual sync, Bluetooth on/off, Orientation lock, Display brightness, Battery level, Free memory, Free storage, and 'flashlight' mode (screen all white).
On the lower right, you see a group of four little icons, provided by Perfect System Monitor:
They show CPU utilization, CPU frequency scaling, Data upload rate and Data download rate.
Along the right edge, you see the dock provided by LauncherPro:
Each icon actually has two functions, as LauncherPro allows a swipe action as well as a tap action. I've added commonly used applications for quick access.
The large widget in the top right is the Android Agenda Widget:
This highly customizable widget syncs to Google Calendar. You can enable any or all of the calendars that your Google Calendar is using.
The wallpaper is from this post: