Watch Movies/ Netflix
Watch movies with your friends all day in your dorm. Set up a time and location, where you gather people from your dorm to watch movies, even if you do not know them, pop some bags of popcorn and get to know each other. This is a way to meet new people, and to be entertained, but not have to travel.
Go to the Library
More than likely you may have some type of school work you need to complete, even if it is not due soon. Why not go to the library and be productive and on top of your course work?
Take a Trip to The Mall
Gather your friends and take a trip to the mall. Shopping is always a good idea when it is raining. The mall allows you to go visit multiple stores at once, and is an all-day event, so why not go on a rainy weekend?
Organize a Game Day in The Dorm
Organize a few different games you could play with other people, and even make it a competition. Play group games like family feud, heads up, or charades. This is a way of meeting new people and passing time.
Workout
What better time to work out than on a rainy day? NONE. Take that trip to the gym you have been pushing back all week.