It's easy - just select the desired access level, copy this link and send it via email, instant message, etc.Link: Just a link to your wiki. Post this anywhere and people can ask you for the invite key.
The 2007 Texas Library Association held in San Antonio included a workshop that I co-presented with Susan Penny and Diane Speer. Here is the Powerpoint link to the presentation that I shared and the direct links that are available to help you with E-books, Podcasting and RSS Feeds: Making a Web-Presence at Your Library.
Also, here's the link to the libraries (these are public libraries, but you get the idea) that use MySpace as a way to generate student interest in the library program. To make it even more confusing, this is actually a wiki...that showcases MySpace!!