Diagram software

Sometimes a diagram says more then a thousands words. That being said, what is good software to draw diagrams? I could quickly draw a diagram on my paper notepad, but known I wanted to visualize my diagram. I tried Dia. Advantage of that software is that is very basic, so you don’t have to waste time on any nifty features more expensive diagram software may have. Disadvantage is the amazingly user unfriendly interface.
Well, I don’t know Diagram Drawing program is the best one, but I did find a nice review of several free versions: Free Diagram Software. There are already several on line versions, which is quite cool.