Skyy

This plugin allows you to banned certain username from making comment, particularly when you don’t want to ban 
ip addresses, but want to stop certain “notorious” misbehaving users.
If your blog requires user registration, you should really try the “members.0.1.1” wordpress plugin.

WP-Ban-User

tcamberlin

IntroduceYou plugin allows you to introduce yourself without having to be registered on the wordpress blog. Talk about yourself, about some project you are supporting or anything you like.
The plugin is availaible on pages, and is displayed thanks to its widget.

Introduce You

IntroduceYou plugin allows you to introduce yourself without having to be registered on the wordpress blog. Talk about yourself, about some project yo …

WP-Ban-User vs Introduce You