Gosh, it's been a while since I've thought about this. We had:
*Burning of the goals: everyone wrote down one thing that they would work to do for the betterment of the chapter, and one by one, deposit the goal in a ceremonial urn. The President would burn them all at the end, with a statement that everyone knew in their hearts what their goal was.
*Secret Sis: when things got crazy, we did a no-frills Secret Sis. No money could be spent, but clues as to who the SS was would be left. The funnier, the better - and the less the two knew each other, the better!
*"Feasts": many times, if we were all (or many of us were) going to the same concert, we would have a "Feast" beforehand in the Suite. Breaking bread with someone really does promote unity.
*Pancake breakfasts: two or three sisters would get up early on a Saturday, and make a major pancake breakfast. There's something about smelling fresh coffee and pancakes that bring people together.
*Going to church together, no matter which religion.
I need to state that, except the first item, nothing was forced or mandatory. Once sisters heard about the fun at one of the events, more would come the next time. There were more, I just can't think.
ETA: We also did the Sharing Ball bit, but that would start out in a Pride, and then move outside of the Pride. It's good to have a few going at the same time, but not necessarily the same days. My roomie & I also did something similar with a trophy I had won. The part that was engraved slipped out of a slot, so we made new names for the trophy, and passed it back in forth fairly often. I'd come home from class, and it would be on my books; Ellen would return from a date to find it on her pillow. It was really fun, and I still have it!