Stopping Spam Registrations as of Dec 2011

Does anyone know what combination of things stops spam registrations with a setup that is using WP3.3, bbPress and s2Member?

I am getting spam registrations. (No problems so far with posts as they have to be approved.) There have been many threads over the past 4 years or so on this topic but I still need some clarification.

1- Is there a plugin that can strengthen the s2Member registration with a required response or that will work and not conflict with the s2Member registration?

2- I saw mention that the spam registrations could still be coming in through the bbPress registration page. There was a reference to redirecting this in an htaccess file but I do not have a clue if this would be the source of the registrations when I am using s2Member, if the redirect would work for my setup or how to do it.

Thanks for any clarification anyone can provide.