Awais

Simple Spam Blocker use honeypot technique which is fast and easy way to prevent spam. This plugin can stop spam comments, spam registration and also can be used to stop bots to try to login into admin panel. This plugin also provide option to stop spammers to get register via Ultimate Memeber Plugin’s registration from. You can also use shortcode [simple-spam-blocker] on any form to stop spammers.

Simple Spam Blocker

Simple Spam Blcoker stop spam comments and also can be used to stop bots to try to login into admin panel.

Denis V (Artprima)

AP HoneyPot WordPress Plugin, based on Jan Stępień’s http:BL, allows you 
to verify IP addresses of clients connecting to your blog against the Project 
Honey Pot database. Thanks to http:BL API you can quickly check whether your 
visitor is an email harvester, a comment spammer or any other malicious 
creature. Communication with verification server is done via DNS request 
mechanism, which makes the query and response even quicker. Now, thanks 
to AP HoneyPot WordPress Plugin any potentially harmful clients are denied 
from accessing your blog and therefore abusing it.
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AP HoneyPot WordPress Plugin

Hard to believe I've been using this fro over 3 years, and the previous one before for even longer. No I wonder this is still being maintained, but still using in the meantime. 

Updated 3 years ago and still works great

AP HoneyPot WordPress Plugin allows you to verify IP addresses of clients connecting to your blog against the Project Honey Pot database.

Simple Spam Blocker vs AP HoneyPot WordPress Plugin