DJ Mystic makes a disco/techno remix of Beethoven's "Fur Elise", so you can have your classical music and dance cred as well.
Also try some classic disco like Earth Wind and Fire's "Shining Star"
Scissors Sisters is good for dancing
"Wonderful Night" by Fat Boy Slim
Limewire has good dance remixes of "normal" songs like "Livin' on a Prayer" and "Billie Jean." Try them out
"Turn Back Time" by Cher ONLY if someone is willing to dress up in a fishnet bodysuit and electrical tape and perform it for you. It will distract everyone from anything cheesy you will play that night!
Believe me -- I am a former raver kid, I know what I reccomend is good.
Oh Oh Oh! I almost forgot! Madonna's "Give it to Me" is my favorite new song of hers.