This is such a sweet thread! I loved reading all these stories... it really reaffirms why going Greek is such a great thing
I have a few. My first one is just a little thing - when I first became a New Member, I was really depressed because of problems with my newly-ex-boyfriend. I left a really sad away message on AIM one day, and returned to my computer to find that an older sister who I hadn't had much contact with had sent me a long message, saying she didn't know what was wrong but wanted to help me through it. She also sent me an mp3 file of a song she said had helped her through some rough times. I listened to it and it really did help - to this day, its one of my favorites. I just remember being blown away by the caring shown to me though I had only known these women for a week or two.
Last summer, I was at work when my Big called me to say my Little had called her in tears. My Little had lined up an amazing internship in a nearby city for the next month, but when she arrived that day, her housing situation had fallen apart. Now she was probably going to have to lose the internship and return home. My Big and I weren't going to let that happen - between the two of us, as well as a number of other sisters, we found her a place to stay for the month and she was able to keep her internship. It was especially memorable because her mom - also a Kappa - was so touched by how strong our sisterhood was.
The final story is actually from another chapter on our campus. A few years ago, before I was on campus, their president was murdered in her apartment. Though I never knew her I still hear about her a lot, and their chapter website has a special page dedicated to her memory. I think it shows a lot about their sisterhood that years after her death, she's still remembered on campus - even by those who didn't know her.