I haven't been to the Yahoo avatar creation page in a while. As the old saying goes, it you don't use it, you lose it. I updated the background for my avatar from a coffee shop to a computer lab background. Then I searched around for how to update it on the blog. I did not find a way.
In fact, I cannot remember how I got it onto my blog in the first place. This is all the more reason for keeping a blog and Google Notebook. If you write procedures down in one of these online places, you have access to the notes from any computer, anywhere.
When I logged back onto my blog for the project, my avatar was there, and the background had automatically updated. It is all connected. This is a good thing, but it's also kind of scarey.