Digg Clone - Drigg

Drigg is script similar to Digg.com. The benefit if Drigg is that it runs on Dupal. So you can add many features to it if you know how to work with Drupal.

Download script : http://www.drigg-code.org/

For a test site, see: http://www.drigg.org or http://www.fsdaily.com

Digg Clone - Pligg CMS

With Pligg you can easily create site like Digg.com. It is very easy to use Pligg. There are many sites which use Pligg. The most popular of them is Spinn.com.

In Pligg stories are submitted, shared and voted for by the users same as Digg.com

Download script : http://www.pligg.com

Digg Clone - PHPdug

PHPdug is a script like Digg.com. It is fast compared to other Digg clones and its completely free.
Download script : http://www.kubelabs.com/phpdug/