It's a little old, but Xiao Xiao does kick ass. I think that last time I checked there were 6 or 7 of them, some interactive. Check www.newgrounds.com and go to Portal. Most of the stuff there is crap, but occasionally you'll find a sparkler. I'd recommend Karma Ghost as well. Very stylish and a bad ass bassline.
edit: Holy Shit I'm linkified! Way to go for us html retards Zims.
(edited by astrobstrd on 2.3.03 0151) Ph-nglui mgwl'nafh Cthulhu R'lyeh wgah'nagl fhtagn
If you're willing to lay down the dough, I heartily recommend the Magic Sing. The songs and lyrics are built into the mic. Just plug it into the TV and go! And now they make a version with two wireless mics.