Antispam Revolution

This plugin:

1. Add 3 hidden fields to Registration form and to Comments form, that only robots can see. Plus you can choose to add validation checkbox to forms.

2. Add to .htaccess file direct access protection for comments file.

3. Check time user spent on page and time when user send a form.

4. Disable trackbacks for past and future posts.

Additionally you can choose to add validation checkbox to forms.