flentini

this couple of filter functions allow to upload image files with only numbers in the filename, avoiding the ‘attachment’ in the URL. ie: www.example.com/category/page/img_1/ instead of www.example.com/category/page/attachment/1/

sanitize image name

allows image files to have only numbers in filename, avoiding the 'attachment' in the URL.

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.

sanitize image name vs WP-Ban-User