Here are two games that are easy to set up, use minimal materials, and are fun for kids about 2-10 years old at a party or holiday gathering.  (See also these knee-bouncing games for entertaining younger kids!)

Pass the Parcel
You will need a bunch of small toys, costume jewelry and similar trinkets, coins, and/or pieces of wrapped candy; a bunch of tissue paper or used-up gift wrap, in at least two different colors; and a source of music. 

Take a trinket and scrunch a piece of paper around it to make a ball.  Place another trinket against the outside of the ball, and scrunch a different-colored piece of paper around it.  Keep going, alternating colors, until you have a parcel at least the size of a football.

Have kids sit in a circle and pass the parcel until the music stops.  Then, whoever is holding the gets to unwrap one layer and keep the trinket.  (The alternating colors make it easier to remove one layer at a time.)  Try to time the stopping of the music such that each kid eventually wins at least once.

Going Fishing
On a big sheet of paper, draw fish swimming in water.   Hang it up such that people can be on both sides: put it on the back of a couch that's in the middle of a room, tape it across the doorway between rooms, etc.  Make fishing poles using sticks from outdoors and string.

One adult supervises a couple of kids standing a few feet from the "water" and casting their lines over it (careful of people standing behind them!) and another adult hides behind the "water" and clips things onto the end of the string using clothespins or paperclips.

Give mostly fish (rubber toy ones, cracker ones, candy ones...) but about every 5th kid throw in something unexpected and absurd and act very surprised when they pull it up.