I need following features without any compromises:
Maximize, minimize (to a reasonable location such as bottom-left corner of the visible page, not in the middle of the screen), drag, resize, etc.
Highly and easily configurable
Actively developed (this can be relaxed a little bit)
Comes with good documentation (and examples)
works cross-browser (I had problems in IE when I tried to use fstoke.me's implementation).
The four plug-ins I have tried failed in one or more respects. I'm not looking for very fancy, animated effects, just very basic but yet adequate functionality.
Go to the demo page to test the different ways to use it. I used this as a base for a desktop project since it has a minimize to toolbar functionality with it.