The last two years Carol has had 20 of her favorite friends over for her birthday. We cooked hot dogs, had a couple flavors of chips, soft drinks, birthday cake. They played music, put a movie on, laughed, talked, just hung out. Twister is a hot game to play. Carol's birthday is in January so it's usually too cold to do much outside. Next year, on her 18th birthday, most of her friends will be able to drive so I am sending them on a photographic scavenger hunt. This was a big hit at James' 18th birthday.
James was born in July so we always had water balloon fights and fireworks at his parties. His group would go out to eat, each of them dutch (they did this at each of their birthdays), and then come back to the house for cake, movies, water balloon fights fireworks and generally just being together.
Both James and Carol have had very successful and popular parties with little expense involved. The kids just like to hang out together. James was never interested in decorating so we didn't but Carol has enjoyed decorating for her parties. Give her some balloons and crepe paper and she has a ball.
One thing that we haven't done yet and may do in January for Carol is get one of those dance games that hooks up to the tv.