It costs $10 (it was $7 when I bought it) and is worth every penny. And they have never asked for an upgrade fee. WindowShade X is by far one of the top 5 pieces of shareware on Mac OS X, IMO.
It started as a simple mimic of the OS 9 Window Shade feature. It has blossomed into much then that. I was content with the simple Window Shade behavior (collapse the window into the title bar) but now you can do many more things, such as collapse a window into a thumbnail version (called Minimize-in-Place), which you can drag around the screen, for example.
The best new(ish) feature in WindowShade X is being able to WindowShade a window by twice pressing the Command or Control key.
I have used WindowShade X since it first was released mainly because I do not like the behavior of minimizing windows in the Dock.
And to be honest I am shocked that Apple has not incorporated this feature into OS X yet, I mean they have clearly stepped on so many other shareware developer's shoes in the past. Can you say Watson? The latest instence of this happening is with LiteSwitch X, which the new Application Switcher looks like, a lot.
Labels X (also by Unsanity) is no longer needed either. On this issue I am sitting on the fence. I would much rather have these types of features built into the OS then have to run 3rd party prefPane's, hacks, and apps to get the same effect. Sure, Sherlock 3 is not as fast as Watson, and does not have ALL the modules of Watson, but I do not have to pay for it. Paying for Labels X is something you should not have to do. Paying for WindowShade X is something you should not have to do. Paying for LiteSwitch X is something you should not have to do. I could go on and on here, there are other shareware apps that have been incorporated into the 10.1, 10.2, and 10.3 releases of OS X.