Commenting

Blogcomments
Free self-hosted commenting system with an ASP base. Layout can be customized using CSS.
http://www.noipo.org/index.php?id=4

BlogKomm
Free commenting script displays comments below posts rather than in pop-ups.
http://www.blogkomm.com

Cbox
Scalable tagging and commenting system that lets visitors leave you messages and talk to each other. Premium version has live chat capability.
http://cbox.ws

co.mments
Uses a bookmarking system to track comments so users can follow their conversations across blogs.
http://co.mments.com/

DocumentRoot Weblog Tools
Free weblog commenter and counter tool.
http://www.documentroot.com/signup.html

DotComments
Server-side, requires PHP. Has its own support email list.
http://tech.groups.yahoo.com/group/dotcomments-support/

HaloScan
Free, easy to install weblog commenting system allowing webmasters to receive feedback on their website.
http://www.haloscan.com

LastHalo
Add-On for Haloscan users to display the latest comments.
http://lasthalo.uzyn.com

Pollxn
A lightweight discussion engine for Blosxom and other weblog/blogging applications. It lets people post comments about your weblog stories right on your site.
http://www.nukekiller.net/pollxn

PurpleBunny
Add your comments to the web page you are currently reading for others who come after you, and read comments from people who came before you.
http://www.purplebunny.com

Reblogger
A comment system for weblogs that can be used as a remote commenting system or can be installed on any server with cgi capability and perl.
http://jsoft.ca/reblogger/

Remote DotComments
Remotely hosted commenting script.
http://www.philringnalda.com/remotedotcomments/

Tag-Board
Free message board for weblog webmasters wanting to communicate with users. Displays inline comments.
http://www.tag-board.com/

Tag-World
A free tagboard system. Displays inline comments.
http://www.tag-world.com

Tara Star's Script
Requires PHP. Notifies the weblog's owner when new comments are posted.
http://old.climbtothestars.org/coding/comments/

YACCS
Free remotely-hosted commenting. Available in multiple languages and does not require JavaScript. Users can edit and delete posts, and ban IP addresses.
http://yaccs.rateyourmusic.com

ZonkBoard
A free blabber board made specifically with weblogs in mind.
http://www.zonkboard.com/