The internet is a massive community. The more someone interacts with it, the more they get from it. Guest-blogs work in much the same way. In the basic scheme of blogging, guest-bloggers are fellow bloggers that you invite to write a blog post on your blog. It is a mutually benefiting thing. The guest-blogger gets exposure to new people and the host-blogger, not only is he freed from having to write a blog post, he often times gets some exposure to the guest-blogger's readers as well. Another benefit for the host-blogger is the fact that the guest post is likely to be very good, seeing as the guest-blogger wants to attract attention.
With all this being said, I want to announce to you, my dear readers, that I have written a guest post! It is a very interesting post. I was able to use an illustration I had always wanted to. So, if you will take a look at it I would be very appreciative. http://jrnova.blogspot.com/2011/12/guest-post-joshua-spotts.html