Forum:Why do some wikis have more features?

I am an Admin of http://nonciclopedia.wikia.com/wiki/Pagina_principale, an italian wiki, and I noticed that other wikis have some features we don't. For example, wookiepedia has an image in the search engine, which we cannot enable. I asked them and they told me it was a special extension for their wiki. Could it be possible for us to obtain that extension? One other question: since we've been having problems with vandals, is it possible to enable editing for registered users only? --Mr.Bean 16:19, 11 February 2007 (UTC)