WordPress.org

The Simple Popup Images plugin allows you to add pop-up images to your Wordpress blog. You put a thumbnail image in your post; if a user clicks on it, a larger version appears in a separate window.

Features that I think are cool:

• Plugin's UI makes it easy to add the image and thumbnail to your post
• Can automatically make thumbnails from a large image (requires the GD library to be installed)
• The resulting popup window can, if you like, vanish the moment the user clicks away from it
• Easy installation

The plugin adds a "Popup" button to the quicktags bar. If you're using the visual rich editor under WordPress 2.1, select the "Code" tab on the editor to see the quicktags. Click the button and a window will pop up. Follow the new page's directions.

Important note for visual rich editor users under WP 2.0: There is a known bug with the "Insert" button. What you will need to do is press the "Preview" button and copy-and-paste the code from the "Popup Image Code" box into your post. You can then close the popup window.