Go to Boston & throw loads of tea in the sea.
References :

Indoor games:

Wii

Spin the Bottle

Outdoor games:

Bacci ball

Shooting a gun at a set up target

Horse shoes

Backyard wrestling

Other activities:

Grilling

Drinking beer

Fireworks, if they are legal in your area
References :

Indoor – Yahtzee, Catchphrase

Outdoor- redneck horseshoes, the one with bean bags, or fun stuff like a water balloon toss.
References :

Play some old-fashioned games…such as marbles, sack races, watermelon seed spitting contests, etc.

Indoor you can do a trivia game.

What about some home-made ice cream?

Good luck!
References :
http://www.easy-party-ideas-and-games.com/fourth-of-july-party.html

Indoor:
Name that tune: Patriotic themes
Musical chairs: set to patriotic music
Movie charades: once again Patriotic themes….IE: The Patriot, North and South,etc….
Guess the Jelly Beans: red, white and blue jellies in a big jar. Just remember to count how many you put in. 🙂
Outside:
water balloon toss
watermelon eating contest
watermelon seed spitting contest
contest of decorating a hat in an American theme. (cheap materials at the dollar store)
Contest of wearing the most colorful, patriotic clothes.

I’ll keep thinking..
References :