Well, I just took a look at the Lucene FAQ and came up with some interesting info:
You can do a wildcard search by putting * after a word to match any string of characters, so in your example searching for "dog*" will return dog, dogs, dogfight, etc. You can also use ? to match a single character, so dog? matches dog or dogs. These examples appear to work properly on our site.
If Joe decides to really tackle the Lucene search implementation and improve it, I'd love to see:
Support for complex queries -- and, or, not (with grouping) -- This would be very helpful here on mojoPortal.com! Joe might be able to implement this according to instructions here.
Addition of the contents of linked PDF documents (self-hosted) into the search index. We have a lot of these.