It is a fact of life that you will have to deal with some spam on any site. There are other ways of combating spam: such as a Q&A Captcha (the site asks the user a question such as "What is the name of the site?" and the user has to answer it correctly: very hard for spammers to get past), but they aren't readily available for wordpress the last time I checked.
This isn't a very good answer, but unless you make some custom plugins for wordpress, your going to be stuck with some spam. And if you make some custom plugins for wordpress, you are going to have less spam, but you still will have some. You can't eliminate spam entirely, you can only reduce it's numbers. The goal is to reduce the number of spam on your site to the point where you barely get any.