Apple released Safari 5 yesterday, with a feature that many people have requested - extensions support. However, some people have had some difficulties understanding how to enable extensions support in Safari 5. To enable/install extensions on Safari 5 for Mac OS X, follow this tutorial:

Step 1: Go to Safari's Preferences

Step 2: Go to the Advanced tab and check the box that says "Show Develop menu in menu bar"

Step 3: You should now notice a new "Develop" menu located in the menu bar of Safari. Click on it

Step 4: Click the option that says "Enable Extensions"

Step 5: Go back to Safari's Preferences and there should be a new extensions button at the top, meaning that you have successfully enabled extensions in Safari

To download extensions, you can visit this catalog of them. Download the file and open it. Accept the message that asks you if you would like to install this extension and restart Safari.

That's it! You've enabled and installed extensions in Safari 5.