Blogger is your easy-to-use Web site, where you can quickly post thoughts, and interact with people in blogs. Now with e-mail notifications--Get feature announcements and tips to get the most out of your blog.
This isn't software, per se, but rather a website. It's very good one at that, one of the best free blog sites I have used. There are a few bells and whistles like a rich text editor HTML and pretty much complete control over how the blog looks (customizable templates). The only complaint I have is that there are only a handful of fonts that can be used. Otherwise, a great site.