The old version of blogger only allows you to archive posts by day, week, or month. This may make it difficult to find or search through posts. Blogger Tips and Tricks
offers a solution to this problem in their article: Blogger Categories - A Simple Method
The new version (out of Beta) makes achiving much, much
easier! Visit my test blog, Teaching a Dog New Tricks
to see how I've been playing with the new version of Blogger.