As SEO is currently a very hot topic and many WordPress plugins dedicated to enhance your SEO are available. These aren't all that bad, and some of them are really good. All in One SEO Pack is one of these and has lots of features to help you with your blog SEO:
Automatically optimizes your titles for search engines
Generates META tags automatically
Avoids the typical duplicate content found on WordPress blogs
For WordPress 2.7 you don't even have to look at the options, it works out-of-the-box; just install.
You can override any title and set any META description and any META keywords you want
You can fine-tune everything
Backward-compatibility with many other plugins, such as Auto Meta, Ultimate Tag Warrior, and others
The All in One SEO Pack plugin can be downloaded from http://wordpress.org/extend/plugins/all-in-one-seo-pack/. It is currently, one of the most downloaded WordPress plugins ever.