Use the Multiple Users to create all the users you want to access your computer (this is the same as the Multiple Users control panel AND the Users&Groups tab of the FileSharing control panel in Mac OS 9). All users except Administrator will belong to group "staff".
Log in as one of the users. Open System Prefs, click the Sharing pane, and click Start to make the user's folder shared.
Here's the way it works: For each user, the user's home folder is a share point. For example, Johnny, Sally, and Sue all access one computer. When Johnny logs in to the serving computer and turns on Sharing, three share points are provided from the computer: johnny, sally, and sue. These are folders which reside in ../Users. Now, when Johnny logs in from ANOTHER computer, he can see all the share points. The privileges work as thus: johnny - read/write to every folder enclosed (that's because Johnny is the folder's owner), sally - read only for every folder enclosed except for ../sally/Public/DropBox. Remember, Johnny logged in as johnny; although he can see Sally's folder, he can only write to her drop box. (Works similarly for Sally's share point, sally.) Every user has a drop box by default.
Now, if you want to customize any of these privileges, just open the Inspector for a folder, and choose Sharing from the Show menu. Change the privileges to suit your tastes. Note: Although you can change privileges, you cannot create share points; each user has his or her own. Another point: Users cannot change privileges outside of the ../Users folder. Only System Administrator (root) can do that.