Akismet API Key is not free for non-personal wp blog or website, find Akismet Alternative WordPress Anti Spam Plugins to Prevent Spam Comments in your blog.
A new useful comment plugin that really works to combat spam bots. I have tried it myself for a few days, this is my review.
A guide if you want to put an IP address on blacklist -Wordpress.
Wordpress tip if you have some problems with people post spam comments in your wordpress blog, by using spam plugins, and set up a few things.
Akismet is one of must have plugins of wordpress and it has to be activated right after you install wordpress blog. Find out how in this post. At the end, you will have Akismet activated and you can also display Akismet widget to display how many spams caught by Akismet.