WP No External Links

It does this in the posts, comments pages, authors page.

Installation:

Unpack and upload it to the /wp-content/plugins/ directory.
Activate the plugin through the 'Plugins' menu in WordPress.

What is new in this release:

• Correct redirection links with GET parameters, sometimes damaged by WordPress output.

What is new in version 3.5.9.8:

• Correct redirection links with GET parameters, sometimes damaged by WordPress output.

What is new in version 3.5.9.3:

• Correct redirection links with GET parameters, sometimes damaged by WordPress output.

What is new in version 3.2:

• Completely removing links from your posts (someone requested this option)
• Masking links to text. Option for perverts.

What is new in version 3.1.0:

• Masking links with digital short codes.

What is new in version 3.0.3:

• Outgoing clicks stats.
• JavaScript redirect with custom text and timeout.
• .po file translation (sorry, now only English and versions are available).
• Full link masking.
• No masking for registered users.

Requirements:

• WordPress 2.6 or higher