HT Games
Charades
The game of charades is one of the oldest and simplest games created, requiring almost no equipment or pieces for its most basic form. There are some board game versions where the players will draw cards to determine what they are supposed to describe, but the game can be played simply by the players using their own creativity. The players can also write their own phrases and have each other draw them. All the players need to know are the basic symbols for introducing something before they use mime-like descriptions to get the others to guess it. For example, putting their hands together and opening them means "book," turning their fist near their head to mimic a projector means "movie" and putting up a number of fingers indicates the number of words.
Pictionary
Pictionary requires only a very large notepad placed on a stand for the players to draw on. The players then draw symbols onto the paper to try to get the others to guess what the drawings represent. It's quite similar to charades, only done with drawings instead of movements.
Trivial Pursuit
If anyone has collected a large number of Trivial Pursuit games and cards, these can be used for a quick and easy game at any time. The game board and "pie pieces" don't even need to be used. Players only need to lay out the many boxes of cards they have, draw cards and see who can answer the most questions on a card. Given the many different themes the multiple card boxes will feature, the players can even pick a theme for each player given that person's area of expertise.