I was recently looking for the easiest way to modify the links list in SharePoint 2007 to open the links in a new window. In my case, every link in a links list points to an external site, so they should all be opening a new browser window.
There were a couple custom features I found, but most required modifying (or replacing) the existing links lists, something that I did not want to do. Anyway, here's how to make the change (note: I modified the original files, this probably isn't a best practice, and the changes could be lost by updates from Microsoft).
First, open the schema file for the links list feature. In my case, it was located at:
C:\Program Files\Common Files\Microsoft Shared\web server extensions\12\TEMPLATE\FEATURES\LinksList\Links\schema.xml
In this file there should be two instances of the following:
<Column Name="URL" HTMLEncode="TRUE" /><HTML><![CDATA[">]]></HTML>
Replace them both with this:
<Column Name="URL" HTMLEncode="TRUE" /><HTML><![CDATA[" target="_blank">]]></HTML>
Then restart IIS (or just the application's worker process), and now all the links in your links lists should open a new browser window!