Witch: Smarter Application Switching
To many people Tiger’s application switcher (Command-Tab) leaves much to be desired. This dislike is mainly because it only switches between applications, not individual windows. Now users can switch windows using Expose, but not as easily as it would be with Command-Tab, because one has to use the mouse when using Expose.

Witch makes window switching much easier and full-featured than the default Tiger switcher. When the key combination is pressed, a “bezel” style window comes up, showing every window, open or minimized, with the title of each window. Witch also allows users to quit individual windows or whole applications by striking simple commands while Witch is open. Best of all, Witch is free.
By default, Mac OS X does not allow command-tab to be mapped to anything else, but with some tweaking, it is possible. This video gives a good tutorial on how to make command-tab your Witch activation key.

Does anyone even use the application switcher in OS X? I certainly don’t.
I use the OS X switcher. It seems to work fine for me. Plus I use command+left aposterphe to scroll through application windows within a single app.
I sometimes use the default switcher. It’s great for quitting a bunch of apps. Just press Q when you’re selecting the app you want to quit.
@Andre: I do…
As for the app… no thanks. Expose is really all I need. A quick flick of the wrist and I have all my windows.
with the little time i hsve spent with macs, i find expose excellent.