Babs,
In the past we've had everything from the owner giving a quick thank-you-speech to all the customers and staff (giving bonuses publicly as well to staff) to taking group pictures of everyone there while playing great classic rock songs, to playing kamikaze-karaoke, beer games, simulcasting the event from tv through the sound system, etc... before midnight. We have also run slideshows of pics from the past year and made future promo-videos by asking people at the party what they had to say about our services.
right after the countdown we usually all sing together a few popular group songs- like 2-3 in a row (ex: sweet caroline, american pie, piano man,etc) while still toasting with champagne and eating the ice cream cakes i would supply.
-the corporate gigs always went right into dance songs- sometimes karaoke songs that were pre-planned to be crowd pleasing dance numbers. I've even hired dancers (besides myself) to teach lines and salsa moves. Everything from booty call, cha cha slide, electric slide, night fever, blame it on the boogie, stayin alive, boot scootin boogie, strokin', virgina reel, happy people, and step in the name of love. Can't forget the Hustle!! Women love to dance as you know and the gents usually follow suit- especially to slow dance songs.
-you can always ask any of your singers if they have any hidden talents they can share to make the party more fun. (dancing, cooking, videos, slideshows, decorations, running secret-santa on NYE instead of on xmas day)
-females sometimes like reasons to bake desserts or prepare dishes if they think they'll be enjoyed by others.
we have also made it a point to give out name tags with their place-of-origin so everyone got to know everyones names and what hometown they were originally from.
...bobbing for apples is also always a fun thing at parties!