We are lucky in the US that we are able to use Akismet to help cut down on comment spam and contact form spam. Yesterday, I had an email exchange with a German citizen who isn't able to use Akismet because of German privacy laws [Correction: This is not against German law, but is a sticky issue because German Citizens' data is held on US servers]. He had to find another way to cut down on all of the contact form spam he was receiving.
After trying a few different plugins, he eventually settled on Cookies for Comments, which takes a very unique approach to cutting down on spam. From the plugin's description:
This plugin adds a stylesheet or image to your blog's html source code. When a browser loads that stylesheet or image a cookie is dropped. If that user then leaves a comment the cookie is checked. If it doesn't exist the comment is marked as spam. The plugin can also check how long it took a user to enter a comment. If it's too fast it's probably a spam bot. How fast can a legitimate user enter their name, email, web address and enter a well thought out comment?
His blog has been spam free since installing the plugin yesterday. So if you ever need to cut down on comment spam without using Akismet, give Cookies for Comments a try!
Thanks to Marco for all his help with this!