Ultrastar, a singstar open source clone for pc written in pasacal and i think it would be a great feautre to incorporate in Amarok. A Ultrastar song editor would also be perfect

Not sure how but there solutions to everything  

http://sourceforge.net/projects/ultrastar/

And I want Amarok to check my e-mail. Not sure how, but everything is possible.

No seriously, I don't think we'll see a karaoke feature in Amarok in the nearest future - it's simply not the application's purpose. Heard of the Unix philosophy?
"Write programs that do one thing and do it well" is one excellent example. Ultrastar is a Singstar clone, Amarok a music player. If you want such a feature in Amarok, I guess scripts is the only way to go.

Hope I didn't sound too harsh