I REALLY love the Tricerasoft Swift Elite Hoster. They also now have a 2.0 version that I have not used yet.
http://www.tricerasoft.com
It is expensive but WELL worth it! It make it so easy to make a super pro looking show. They even have a free working demo of the software you can download.
Another thing is they support things like DJ console controllers and DMX lights!
and if you buy an ATI All-in-Wonder video card it comes with an RF remote that works with the software.
they also offer a CD+G ripper so that your entire karaoke library can be searched and cued in literally seconds.
You can also type in who the next singer is and it displays on the screen so they can get ready.