I guess we're pretty lucky, on our campus the fraternities and sororities get along with one another pretty well, with a few exceptions.
For instance, one fraternity will start rumors, such as saying that another fraternity tried to start their house on fire, and other nasty stuff. They often think that they are better than others, and think they deserve some special status just because they joined a particular chapter. For this reason, I try to avoid them and am as cordial as necessary when I have to interact with them.
On a lighter note, two of the four sororities have a slight rivalry that started from the Greek Awards this spring. Pi Phi beat AOPi for grades, but AOPi won the award for top sorority chapter of the year. A funny story that arose was when Pi Phi came to serenade us, they turned toward AOPi's house and put a line in the song that said "cuter than any AOPi!"
Then as we returned the greeting, we accidentally did a cheer for AOPi instead of Pi Phi!
Those girls were pissed off and shocked! I apolgized to a couple of them later that week, so hopefully they aren't still upset after all this time!