For my daughter's 9th birthday we had a karaoke party. I rented a karaoke machine with 2 microphones (plus popular CDs). We decorated the room with posters from TeenBeat magazine and other magazines with pop group photos. Metallic paper stars were suspended from the ceiling.  The "stage" was set up in a corner and we hung metallic skirting on the wall to look like curtains. A revolving disco ball with lights was set up as well as balloons. I purchased inflatable guitars, keyboards and saxophones from a local party store which served as props while the girls' sang.  Prior to the party my daughter and I went to a thrift store and purchased inexpensive "disco" clothes and prom dresses for the girls to dress up into to get into character. A separate table was set up for fingernail polish and makeup if they wanted. Food included chicken nuggets, goldfish, etc.  The cake had music notes on it and the lyrics from ABBA's "Dancing Queen". The girls had a BLAST--it was the easiest birthday party I have ever planned--they entertained themselves the entire time with the karaoke machine!  Goodie bags included the inflatable instrument, a plastic disco-like hat and a pretend microphone plus candy.  It was such a success we are doing the same thing this year but adding a singing contest and dress up contest.