For double chocolate chip cookies, reduce the flour to 2 cups and add 1/4 cup of cocoa powder.
For marble cookies, make a half batch of regular chocolate chip cookie dough and a half batch of double chocolate chip cookie dough. Then, when ready to form the dough into balls, take a small scoop of each type of dough and roll them together to create a marble cookie.
For m&m cookies, use 1 cup of mini m&ms instead of the chocolate chips.
For white chocolate macadamia cookies, use 1/2 cup white chocolate chips and 1/2 cup macadamia.
For snickerdoodles, add 2 teaspoons cream of tartar during step 3, omit the chocolate chips, and roll the cookie dough balls in a cinnamon sugar mixture (1/4 cup sugar plus 1 tablespoon cinnamon).
