This is an idea for a plugin:
There is an old plugin for Answers.com that makes te visitor able to check the meaning of any word in the blog only by double clicking on it. You can see aan example here in this blog:
http://media.www.lakelandmirror.com/media/storage/paper471/news/2006/03/30/Opinions/Do.Weblogs.Count.For.Libel-2011701.shtml
just double-click on any word. You get the meaning in a box.
What I have in mind is something similar for Wikipedia. It would be great to give the visitor the ability to check Wikipedia without leaving the site.