Depends on what sort of party actually, if you want to have one where everyones dressed up really sluttily, then school uniforms/angles and devils would be the way to go. Just a fun sort of party where you can have a laugh, then masquerade, superhero, monsters etc.
I don't think I've ever been to a proper themed party, it's always fancy dress in general.
The 80s would be blingtacular, imagine the costumes. Imagine the hair. There was an 80s-themed disco thing on one episode of Even Stevens and everybody looked incredible.
had a brilliant party last summer - themed it moulin rouge. pretty gd fun...check the pics out if you want to see how OTT some of us were!! (my id photo thing is from the same party a bit later on in the evening!)
films with masses of different characters like that can be quite gd fun i reckon