Cocktail party games are both icebreaker and entertainment. They provide a convenient way for people to meet and mingle, and an easy way to pass formality by and have your guests go straight from stranger to friend. For old friends, cocktail party games can provide fresh new ways to interact, preventing folks from getting stuck in the same old conversations. Either way, games can help start your party out on the right foot.
This game requires a little bit of pre-planning to work, but it can be a lot of fun if your guests are amenable. Have everyone send you a photo from their childhood before the party and post them on a board in the middle of the room. Once the guests come in and mingle a bit, gather them together in front of the display (it helps if you have food nearby). The guests then take turns guessing which photo belongs to whom. For an added challenge, make the guests try to guess the year the picture was taken.
Come up with a list of characters beforehand--they can be professions such as astronaut or psychiatrist, historical or current famous figures such as George Washington or Frank Sinatra, or strange quirks such as "compulsive liar" or "man who talks too fast." Each guest has the name posted on his back. The other guests talk to him and interact with him as if he is that character. Each guest tries to guess who he is. If he guesses correctly, the other guests tell him. Alternately, give each guest a sheet of paper with his character on it and have the other guests try to guess who he is.
Exquisite corpse is a game invented by the surrealists, and is perfect for creative groups at cocktail parties. Fold a sheet of paper into three sections. The first person draws a head on the first section, then folds the paper over so that the head is hidden, but the middle section of the paper is exposed for the next person. The next guest then draws the midsection of the body on the second section of the paper, folds it again to hide what she drew and passes it to a their guest, who draws the lower body. The guests then unfold the paper and look at the strange and funny looking creature drawn on it. If you have a big group, start several exquisite corpses at once and keep them circulating. At the end of the evening, allow each guest to take one home.