Bring a deck of UNO cards. It is a great game for camping. It's kind of out of season but look for batarie operated LED christmas lights. I string them around the ceiling of the tent, and then everyone has light behind them so they can see there cards. A lantern in the middle will always leave your hand dark.
Hit up the 99 cent store and grab a bunch of glowsticks for the campsite. I found a ball there thats awesome. It's a bunch of the skinny bendable glowsticks that fit into a Hub and makes a beach ball looking thing. Hang it from a tree, and when the wind blows it will sit outside just spining away. You can find light up frisbees at your local camping stores like REI.
If you have kids with you, pick up a lil bit of information on leave no trace to go over with them. You might want to do that for the adults too. Get some kind of group trash solution, like a can you can leave by the table. Just empty it before everyone goes to sleep.
Read up on some campfire songs and ghost stories. Of coarse any storie you find happened in this forest on a night like tonight. One really good one was originally a couple in a car, making out in the boonies, but it ended with the guy leaving for some reason, and then a storm rolling in. All night she could hear the rain slowly driping, and branches brushing against the roof of the car (or tent for your purpose). In the morning the cops woke her up and told her not to look up as she got out of the car. The guy was hung from th tree above the car, blood driping from his mangled body, and his toenails were scraping against the roof. Fill the rest in yourself. And then if you are really mean, scrape a branch across the tent and drip water on it before you get back from the bathroom in the middle of the night. Make sure you accidentaly woke your tent mate on your way out.
Keep a small pile of rocks hidden by your spot at night, and slyly toss them into the brush behind the campsite so everyone thinks theres something in the woods. If they say why arent you looking with us, tell them you aint going out there. It works really well if you have a partner that can toss rocks while there looking at you. I did it to my fellow camp counselors last summer and they were all freaking out. Make sure there has been talk about bears or mountain kittys earlier that day.
Oh camping is so much fun, especially with a group of good friends. Get a bunch of people together with a good sense of humor and it will be an awesome trip.