I just put
nokia,viagra,qtek,sidekick,.com,www,free
Notice I put www and .com, just to double-protect against spammers.
I also added a couple required fields for all new users to enter, such as "Are you a robot (enter no)?" and "Do you want to register? (enter yes)" to make it less likely for a script to register automatically. Between these filters and the plugin mentioned here, I probably haven't had spam on my forum for over 6 months. We still ban a couple users each day for signing up and attempting to spam though.