Not to repeat but…
At Christmas my family plays the game very similar to how Erica described. Everyone gets in a big circle and all the presents get put in the middle. The presents must be wrapped in newspaper so that you don't know whose gift your grabbing (plus you may end up grabbing you own in all the excitement). Everyone brings at least 2 items (usually much more) it can be something nice, something regifted or something cheap (many in my family are school teachers and often have lots of stuff they've received as gifts that ends up in the pile) but there are always some really good gifts. You take two dice (or depending on the number of people (we usually have 30 people) you could use two sets and roll the dice and have them go in the opposite direction. We play if you get 7, 11 or doubles you grab a gift from the pile or from someone else’s pile. Once all the gifts are gone then there is a speed round 3-5 minutes where the dice go around again and now you steal from anyone you want. This is where it gets really fun. There are usually a few gifts that look like they are something really good that everyone wants!! I would definitely suggest playing this game with a large group. It is always a lot of fun.
Otherwise, I know that at my work for our holiday party we do it where you spend $20 on a gift, all the gifts go in the middle. Numbers are drawn, you go in order of your number. The first person picks a gift and opens it. The next person can either pick a gift from the middle or take a gift that is already opened from someone. If someone steals your gift then you have to take a new gift from the middle and open it. The game ends with the last person who either steals a gift or gets the last unopened gift. The most common gifts that are taken from someone are gift certificates or bottles of alcohol .
I guess it really depends on how much you want your guess to bring/spend. Hope you have fun however you decide to play!