Music swap: Ask friends to come over with their favorite songs, make sure you have speakers set up for all to hear, and listen to some jams all night.
Board-game potluck: Invite over a handful of friends, and ask each person to bring his or her favorite board game plus a snack to share. Take care of the drinks yourself or ask guests to pitch in if things become costly.
Nail party: Do something different from the usual movie or board-game night this weekend — organize a nail party with your girlfriends. Use this as an opportunity to try out fun nail art that would cost a lot of money to get done in a salon
Magazine article club: This weekend, instead of hosting a book club, plan a magazine article night. It's very simple: just pick an article you find interesting and ask your friends to read it too. Then you can all come together over a glass of wine to discuss what caught your attention, what was missing, and more.