How to List All Blog Authors on a WPMU Site

We’re often asked how to display a list of blog authors for WPMU. This piece of code does exactly that. Drop it into one of your theme’s template files wherever you want it to display:

{code type=php}

Then you can edit the parameters as shown below:

exclude_admin: 0 (include the admin’s name in the authors) / 1 (exclude the admin’s name from the list)
optioncount : 0 (No post count against the author’s name) / 1 (display post count against the author’s name)
show_fullname : 0 (display first name only) / 1 (display full name of the author)
hide_empty : 0 (display authors with no posts) / 1 (display authors who have one or more posts)

Source: Blog oh Blog