There's also
MacOSXHints, which has a huge archive of cool things you can do, both with the terminal and without. Just start browsing the archives.
My favorite one from there is the following, which adds a cool transparency effect to hidden apps in the dock:
Code:
defaults write com.apple.dock showhidden -bool true
Then, login and logout or force the dock to restart!
If you don't like it, run the same command with "false" instead of "true" to get the Dock back to normal.