How to make Chrome open a new window for external Links

You can try using the AppleScript found on this page.

I just tried it out and it perfectly works fine in Chrome 12.0.742.122.

It's extremely easy to set up:

• download the Bundle archive
• double click it to unpack it
• double click on OpenUrlInNewChromeWindow
• open Safari and set the new "Browser" as the default browser in the Preferences.

Starting at Dave’s answer, I found that with Chrome 45, running osascript is no longer needed, and that with OS X 10.10, the Apple Script is not selectable in the system preferences. Here is how I solved it.

Create an Apple Script using the Apple Script editor, and export it as an application.

on open location theURL
   do shell script "/usr/bin/open '/Applications/Google Chrome.app' --new --args --new-window " & theURL
end open location

Install RC default app.

RCDefaultApp is a Mac OS X 10.2 or higher preference pane that allows a user to set the default application used for various URL schemes, file extensions, file types, MIME types, and Uniform Type Identifiers

In the system preferences, open the new default-apps screen, go to the URL tab, and set the exported Apple script as handler for http and https.