Aksimet is a paid anti-spam comment service that comes standard with your WordPress installation. As it is the standard for dealing with comment spam in WordPress, but it is a paid service.
A combination of the following two plugins has proved to be a great free alternative to Akismet:
Antispam Bee (Don’t let the German scare you, the plugin does run in english in the WordPress Admin)
Bad Behavior
Installing both of those plugins will make a huge improvement with processing comment spam. Both are free, so give them a shot.
If you have any other alternatives to handling comment spam in WordPress, feel free to leave a comment.