The stage is the centre of Blue casket and it brings a great element to the game. You can read your own poems with Manny (the main character) or convince Olivia to share some of her work. It's quite interesting. There is also things to do in the club, such as sharing wide words with some of the customers.
If you want to hear what it sounds like in the club, I suggest you to venture to the links section and travel to grimfandango.net. You can download the Blue Casket Bebop there.
Click on the small pictures to see the whole pictures of Blue Casket.