Social Games: What are some interesting games that four people can play which reveals a person's personality?

Indian poker.

There is a game called True Colors that does this. Note - it's dangerous to play with your family. The game asks questions like, "Who is the least likely to forgive?" Every player then casts two votes for the other players. After everyone votes, the votes are tallied and the person with the most votes gets a point. The questions are tough and get right at the core of those playing. The second is Would You Rather? It pits two opposing things of difficult choice against each other. The player chooses and based on that choice, you get some insight into their personality. For example, "Would you rather be homeless for a year or be in prison for a year?"

Mafia! You need to be slightly more than 4 players though. It's hands down my favorite game ever. A game involving trust, sacrifice, deception and loyalty. You'll get to know your friends on much deeper levels after this. I actually got to know my last girlfriend through this game. Tutorial (you can exchange the deck of cards for simple paper and pen):

The best game for you 4 to play is Dungeon & Dragons.Its a role playing game where you all gather around a big table with a person being the Dungeon Master(Or the creator of the scene or game play.) Then the three of you will be players with your own character solving problems and eventually you will become great friends and will eventually know each others personality.