I've been using command-tab to switch apps for years. First with Microsoft Office Manager, then with Keyboard Maestro. When Jaguar came out, I was dismayed to find that I had been locked out; command-tab is reserved solely for the dock. Although you can command-tab through the open apps in the dock, the interface just isn't nearly as good as Keyboard Maestro. Yeah, I know I can re-map the Keyboard Maestro app switcher to a different key combo, but command-tab is hardwired into my brain. Well, after much disappointment, I have solved the problem.
Since I use DragThing for pretty much everything, and hardly use the dock at all, I killed the Dock. You can find out how to do this from threads such as this one on the forum site. [It was also discussed in this hint earlier this year. -rob]
Once the Dock is dead, you can use command-tab for whatever you please! You still get a warning from Keybaord Maestro when you choose that key combo, but now it works! Of course, this is of no use if you have to have the Dock but, if not, it's a good solution.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20021008062540616