Found a good description of why to use a blog.
This is from the creator of http://www.jotform.com/ where you can create forms online easily.
http://atank.interlogy.com/blog/?p=3
My first blog ever, originally for the LearnScope 2006 project, and which is now the sometime record of my journey into learning about and implementing an elearning strategy for my training organisation
Found a good description of why to use a blog.