My husband works for a large dot com. They have awesome Christmas parties.
The companywide party is adults only and held in a large venue in San Francisco, and everyone gets a hotel room in SF for the night. They always have a major theme and go way over the top in creating it. Last year was pirates and they had a pirateship in the center of the room. the year before was Hawaiian complete with volcanoes and full sized live palm trees in the room. Great food is served all night. They have an open bar, but the highlight is the martinis named after the company that they serve by pouring down an ice sculpture into your cup (which is rimmed with sugar in the 2 company colors). They have awesome bands come perform every year (big ones, that have songs on the radio at the time) and a casino that you gamble in using chips you get when you enter and you take you proceeds and put them in drawings for prizes donated by the websites sponsors (things like roundtrip tickets anywhere in the world, free ipod, free cars, etc). Its soo much fun.
Then the department has a party at one of the bosses house for the employees and their families. Thats much more low key but still fun.
The day before Christmas break they have a party for the kids in the quad of their "campus" and hand out lots of treats (usually have cotton candy machines, gigantic lollipops, etc). The two founders walk around and personally give each employee a gift that they get in addition to their bonus (last year it was a jacket with company the logo, the year before a blanket with snowflakes on it that had the logo hidden in it, before that an official Monopoly game that was made about the website).