edward_plainview

When entering a comment the plugin will load some Javascript values – unique for the visitor – to ensure that the user is a real person.
If Javascript is not enabled in the visitor’s browser, an error message will be shown when submitting the comment.
The spam protection is not enabled for logged-in users.

Plainview Comment Antispam

Prevent comment spam automatically by using Javascript.

bgribaudo

Attempts to prevent automated SPAM by requiring visitors to answer a question of your choosing in order for their comment to be accepted. Presumably, spambots will be unable to correctly answer this question and so comments they attempt to post will be rejected.
Only regular comments from non-logged-in users are filtered. Pingbacks, trackbacks and authenticated users will not be prompted to answer the verification question.
Privacy Note: This plugin does not call home or communicate with any external servers or services. All processing is done locally within your WordPress site.

Super Simple SPAM Stopper

Prevents automated SPAM by requiring visitors to answer a question of your choosing (plaintext or regex).

Plainview Comment Antispam vs Super Simple SPAM Stopper