According to recent data from Akismet, some 89% of all blog comments are spam. If you're running a blog with unmoderated comments without some sort of anti-spam measures, your signal noise ratio is going to be a mess and your comment threads will be virtually unreadable.

The good news is that two of the best options for controlling spam in your comments are free for personal blogs, and one has just a modest fee for commercial blogs.

Akismet is the veteran in the space. It's currently on version 2.0 and has been around for nearly three years of continuous refinement. While it was initially developed for use on WordPress, it's been adapted to run on 20 other blogging and content management systems. Akismet is free for personal blogging and costs just $5 a month for commercial blogs.

The new kid on the block is TypePad AntiSpam. TypePad AntiSpam is just a few weeks old, but it's already garnered some very positive reviews. Michael Arrington of the respected tech blog TechCrunch gave it a weeklong test as an Akismet replacement, and said the following:

After a week I'm pleased to say that as good as Akismet is, the TypePad product has performed as good or better for us. ... For now, we'll stick with TypePad, and continue to report on how it's doing.

TypePad AntiSpam is from Six Apart -- the company behind TypePad and Movable Type -- and it runs, unsurprisingly, on both. It also runs on WordPress and has an open, Akismet-compatible API, so an ambitious developer could extend its functionality to virtually any other blogging platform or content management system. TypePad AntiSpam is free for both personal and commercial use, although you should note that it is still in beta.

With two great options such as these, it's easy to make sure that the comments in your blog are virtually spam free. There's no excuse -- you owe it to yourself and to your readers to keep the junk out of their comment threads.