I posted this in another thread, but thought that others might be interested:
I've built a number of touch screen juke boxes over the past few years. 
Most were built using Micro Industries touchscreen kiosk computers such as this: 
http://www.microindustries.com/products ... ige17.aspx 
These usually have ELO touchscreens which are the most reliable, and have a glass touch surface, rather than plastic, which wears out: 
http://www.elotouch.com/ 
There are a number of different software choices, and some of them will do karaoke here's a couple that will do karaoke: 
http://www.multijuke.com/index.php?item=features 
http://www.thejukeboxer.com/ 
Most of the juke boxes I built were not used for karaoke, so I used Party Time Jukebox software, because I liked the interface the best. 
http://www.partytimejukebox.com/index.html 
Here's a picture of one of the larger units that I made: 
http://www.flickr.com/photos/22794316@N03/2355910672/ 
The units were generally built into a wall in the home and had other software and home management capabilities. 
If you are really serious about doing this, please contact me, as I have the components to put these systems together, or can help you find sources.