There are more MacOSX keyboard shortcuts on the Apple support site.
Tuesday, January 27, 2009
Windows to Mac tips part 3: switching between apps
If you're used to alt-tab on Windows, then you can use cmd-tab on MacOSX to switch between applications. Note that Windows switches between all open windows for each application, whereas the Mac only switches between applications. If you wish to switch between windows within one application then you need cmd-backquote (cmd-`) although I've found that this doesn't work in all apps.