With MT you can have multiple authors on the same weblog, making it easy to have a friend contribute to your blog as a "guest author" or to create a group weblog to which many people contribute. You can even customize to a small degree, aspects of the author-specific Individual Entry pages.
Adding an Author
To add an author in MT 3.2 open up the Main Menu of your weblog edit window and select "Authors" from the System Shortcuts menu. Click on the "Create New Author" link. In the "Create New Author" window, type in the Username - the name with which the new author will use to log in to the system, the Display Name - the name which will be displayed when the author makes a post, email address, and password (twice) for the new author. Check the boxes associated with the blogs for which you want the new author to have permissions. Save changes. You will be taken to the Author Permissions page for your new author. Select which general permissions you want this author to have on all of the blogs in the system. Check the specific permissions you want this author to have associated with each blog. Save changes.
To add an author in MT 3.1x and earlier versions, open up the Main Menu of your weblog edit window and select "Add/Edit Weblog authors" from the Shortcuts menu. In the "Add an author" window, type in the username, email address, and password (twice) for the new author. Select which blogs on your MT install for which this new author will have authoring privileges. If you have only one weblog on your MT installation, select the checkbox next to it. Click "Save".
You will now be able to set the author permissions for this new author on a weblog by weblog basis. Typically for guest authors I only select the "Post" and "Upload Files" permissions. For group weblogs I may or may not have more permissions checked. It depends on how actively involved in the behind-the-scenes blog maintenance I expect them to be. I would only give "System Administrator" (v3.2) or "Edit Authors and Permissions"(v3.1 and earlier) permissions to someone I completely trusted.
Your authors will now be able to post to the weblogs for which they have permissions. Direct them to your Main Menu weblog edit URL (the one that ends with mt.cgi). Have them sign in with the username and password you have assigned them. If you have given your authors "blog administrator" privileges they will have visibility to the author menu and will be able to edit their author profiles. Note that if your guest authors have different permissions than you, they will see a slightly different version of the menu screen. They may not see other weblogs for which they don't have access, for example.
Movable Type 3.15 (and earlier versions) does not have an easy set up for author archives as it does for monthly and category archives. You can get around this; the method is kludgey, but it works.
To create a page that lists the entries of only one of your authors, create a new Index template from your template edit window. Copy and paste the template code from your Main Index template into this new template. Change the <MTEntries> tag to <MTEntries author="Michelle">, swapping out "Michelle" for the MT username of the author you want to use. Create a name for the template that includes the author's name for easy reference. Create an output file name that includes the author's name for the same reason. Save and rebuild the template.
Repeat for every author. (You can see how this method is not particularly scalable.)
Point to the author pages by hard-coding the links to the individual index pages from your Main Index.
David Phillips, a.k.a. Tweezerman, has some other methods listed on this thread in the MT Support Forums.
Shelley Kaufman, a.k.a. Girlie, has outlined a method to create author archives using dynamic publishing: Dynamic Archives by Author.
Customizing the Individual Entry Template on a Per Author Basis: example
When I first started including tutorials from guest authors I faced a dilemma. How to have each author's copyright or creative commons license automatically appear on the tutorials they authored?
This can be accomplished using Template Modules, MTIncludes, and the MTIfEqual tag.
2. Create individual template modules for the License rights for each author. For example, in the case of this weblog, the following is a template module named, Rights Elise:
3. Add the following code to your Individual Entry Archive template where you want the section to appear, substituting "Author1" and "Author2" with the user names of your blog authors. Substitute "Rights Author1" and "Rights Author2" with the names of the template modules you have created with the individual license notices.
4. Save your template and rebuild your site.
Now when different authors post, they can have their license information display automatically. An example of this in action is the Converting to PHP tutorial that LMT guest author Sarah Hughes wrote. Note the license info at the bottom of her tutorial. This license information gets displayed automatically on any tutorial that Sarah authors on LMT.
This method can also be used to serve up Google Adsense or Amazon Ads that have the account information for the guest author, or any other author specific content.
MT Manual on Authors and Permissions
MT Manual on Miscellaneous Tags, the MTInclude tag
David Phillip's work-arounds for author archives
Brad Choate's MTAuthor plugin
Customizing Google Adsense ads by author using PHP
Dynamic Archives by Author