There is a wp-stats hack that will do this and more. Look for it in http://wiki.ww.wp.xz.cn when it starts working again.
If you’re the only author of the blog, then you can simply insert the following wherever you want the total post number to be displayed:
<?php the_author_posts() ?>
Here is a plugin that will display the total number of blog posts, comments, categories, or any combination thereof. May be used inside or outside of the loop:
BlogStats PCC
