I had a fifties Party for my 7 year old last year. WE hung old records from the ceiling by fishing wire, contacted the radio stations for prizes: bumper stickers, key chains ect., played music from Grease and other 50's artists, made balloon poodles, had everyone dress in character, had a dance contest, a hand jive contest, a best dressed contest, and a limbo contest! The winners won prizes from the radio station (big ones like T-shirts and CD's). Everyone went home with the small prizes.  We had a Cookie cake that was designed to look like a record and had root beer floats and ice cream sundaes they made themselves. Everyone had a ball and the party was a big success!!  Invitations were copy paper cut out to look like a record and the text was written around the record to look like a record. In the middle I wrote Brieanna's 7th Birthday "It's My party and I'll cry if I want to." to make it look like a real record with the title.