I am working on a module called the Course Manager. This will hopefully morph into something more of a "Multisite Manager" (though that name space is already taken for such a module, this is more advanced). This talk will be all about architectures that you can setup and structure to make your life A LOT easier as you scale in the creation of [more and more] Drupal sites.
This would probably be good as a show-and-tell and then break down into discussions of how others are using multisite setups and to help others through the process of understanding them and getting them up and running. I'll be going over the module that I've been working on lightly and focusing more on the structured approach to database / site naming conventions and how it can lead to a massive simplification in user / site management.
This makes the most sense in an educational setting with a lot of related sites / departments / colleges (this is currently in use at Penn State College of Arts / Architecture and is spreading). This can also be useful for those creating sites within the same network of sites for any company to simplify user and role management.