My main in-tent entertainment is:
1. Sleeping.
2. Killing all the little flying nasties that follow me in.
3. Skunks - even more entertaining when it's not my tent.

All kidding aside, I tend to go to bed when it's dark, and get up with, or just before, the sun clears the horizon. Sometimes, I'll spend a few minutes looking at tomorrow's route on the map, or even bring a map for somewhere else and plan the next trip.

In my younger days, when I traveled with others and shared a two-person tent, I'd take a deck of cards. When solo tents became available, and I began hiking solo (or with someone who is like-minded about bedding down and rising early - in his solo tent), the cards stopped going along.

On a clear night, when I don't need/want the fly on, stargazing through the roof of the mesh inner tent is a nice way to drift off to sleep.

For sheer amusement, usually before tent-time, you can't beat watching folks try to set up a bear bag.