Spam comments are a huge problem—more so if you have even a moderately successful website. You will find your WordPress blog or website being attacked by spam comment bots. Adding a Captcha to the contact and comment forms does reduce the amount of spam, but it also is a pain for users.
BotBlocker is a WordPress plugin to beat spam without inconveniencing your readers/users. It uses the honeypot spam-prevention technology. It tricks and traps spam bots by giving them a challenge that human users can not see.
BotBlocker swaps the positions and replace the names of the form fields for your comment forms with random fields. On the screen, human visitors will see the email field and enter their email address. However, bots fail to spot the correct fields and end up providing wrong data. WordPress will not process the comment until email is entered in the proper format.
However, Botblocker does not protect you from manually submitted spam. You will still have to use a plugin like Akismet to beat those guys.