SmartBars are just applications that cling to a side of your screen like the way Windows Task Bar does.  I typically use it to quickly access folders and applications instead of navigating the Start Menu.  I found two SmartBars via Scoble, SmartBarXP and Desktop Sidebar, and decided to try the SmartBarXP (looked better than the other one).  Nicely done although it's not quite commercial product quality yet.  It comes with 14 gadgets ranging from MP3 player and system resource monitor.

SmartBarXP's main problem is that it is too big and slow for a program intended to be running all the time.  It eats up 24 to 32 meg of memory and responds slowly when interacting with it.  I thought it might be written with .NET, so I took a look at the binaries and found that it was written in Visual Basic 6.  You can build nice programs with VB, but not when you need minimum impact on memory and CPU.