I made these by spreading a thin layer of frosting over the entire cupcake. Then I spread some black frosting over the spot where the eyes would go (brown or chocolate frosting would also look good and may not bleed as black tends to do after a while). I used a #44 tip (you can also use a basketweave tip with the textured part facing down and flat side up) to pipe lines across the cupcake, leaving room for candy eyes. If you don't have candy eyes, just pipe some white with a larger round tip and then black with a smaller round tip.
These were the most popular of my cupcake tray. I piped the base white with a 2D tip and added Oreo crumbs on top for texture. I then cut long black licorice strips into pieces about 2 inches long, slid them into the frosting between the layers of the Oreo and attached candy eyes with a dab of frosting. If you don't have candy eyes, pipe some white and add mini m&m's or a dot of frosting for the center of the eyes.
Melted Witch Cupcakes
Rejoice! The Wicked Witch of the West is dead! I made the witches hats with a Keebler's Fudge Stripe cookie turned chocolate side up with a chocolate kiss on top. I piped a bow with a small writing tip and placed on top of a swirl piped with the same 2D tip as above.
I made these cupcakes by frosting a pumpkin cupcake flat in orange. I angled my spatula to add some lines up the sides of the pumpkin. Then I placed the "stem" (an inch-long piece of pretzel rod dipped in chocolate) in the center and piped vines and leaves.
The bat is a Wilton candy mold that is a pick that sticks in the cupcake. I molded the bats with Merkins black chocolate (which amazingly tastes like Oreos) and placed the picks into the cupcakes after topping the cupcake with the 2D tip and adding some festive sprinkles.
Some other inspiration I found after-the-fact:
Which are your favorites?