The Talk module might be what you want. It places all the comments on a separate page like Wikipedia.

From: support-bounces@drupal.org [mailto:support-bounces@drupal.org] On Behalf Of Jack Tuhman
Sent: Tuesday, July 15, 2008 7:32 PM
To: support@drupal.org
Subject: [support] separate page for comments

Hi list,

Is there an easy way to move all the comments to another page.   Almost like having 2 pages for nodes, one with comments one without.  I would love to be able to do this entirely or almost entirely in the theme.   I might be able to do it with a hook_comment, but that has a large overhead, that I would rather not have.

Thanks for the help,
Jack