This is quite simple actually. You've got to somehow convince (or coerce, your pick) your boyfriend that it is in his best interest to join you in the various activities that make you happy. I'm guessing you're a nice young lady since you are allowing this to go on. My guess is you ask him to do something and he says he doesn't like doing that and its the end of the conversation. Then you probably just hang out with him watching college football and switching to vh1's Tool Academy at every commercial break. This blows, especially for somebody like yourself who likes going out and doing things.
I think your boyfriend is too comfortable. So I have a few suggestions:
1) Just leave and go do what you want with your friends. Sure you'd rather hang out with him but he's not willing to try so force his hand. He'll start to complain and you'll be able to show him that you mean business. If he fights you on it and refuses to do things you like, he's not the guy for you anyway. Trust me.
2) Throw a fit. Most men will do whatever it takes to shut you up, to include things we really do not want to be doing. You'll definitely get your way then. However, I have to caution against this as you get branded as a whiner and a malcontent and you'll surely break up soon enough.
3) Turn off his cable. Drastic, I know, but if you've ever been at work when the network goes down, people drift into the hallways and speak to people they've never spoken to before. He'll leave the house, guaranteed.
All in all, I'd just suggest letting him know how you feel and compromising. Tell him that you don't have to go out all the time, but at least some times he needs to be more willing to do what you want. If he's got a problem with that, drop him before you end up sitting in the same spot 20 years from now wondering where the last 20 years went. Men don't change unless we have to.