This is a good way to sneak something healthy *gasp* into your All Hallows' Eve festivities. It takes mere minutes to make these, and they're just as fun to eat. Also, this makes a safe and relatively mess free project to work on with kids.
Step 1: Harvest "pumpkins" & gather tools
This part is entirely dependent on your personal preferences and what's available and in-season at your local market. For this instructable we chose to go with the humble mikan, but really any smallish, oblate, orange citrus will do: satsuma, clementine, tangerine, mandarin or other diminutive orange. These closely approximate a pumpkin in shape, though not in size.
If you want something with a bit more heft to it, a regular sized sweet orange or tangelo might work, but as these have a tendency to roll around it would be best to keep them in a bowl. If you're working on the 'small is cute' principle, you can even up the ante with kumquats.
Basically we are talking Sharpies here. Colors are at your discretion, but black is basically all that is really needed.
In order to make up for the lack of a real pumpkin we're going for scale here. The more citrus you can get your hands on the better. Cost comes into play too: if you figure an average pumpkin will run you $6 - $10 at the grocery store, you can spend the same amount and get a case or two of citrus at about the same price - plus you'll actually eat the citrus. We'd all love to say that freshly carved pumpkin becomes freshly baked pie but I'll be the first to admit that mine usually end up moldy and double-bagged in the trash bin. Tiny oranges, however, you'll have to keep from disappearing before Halloween rolls around.
Step 2: Give 'em a bath
What you're really getting at is trying to remove some of the waxy film on the outside of the citrus; I find that this helps the permanent marker adhere better. Just a quick rinse and some light rubbing under water will do the trick.
Stick your washed oranges in a strainer and let them dry thoroughly.
Step 3: Painting by Sharpies
A note on technique: lightly dabbing with the tip of the marker will give you a darker and more even coat than broad swaths with the pen tip. Think of it more as painting - small controlled strokes will give you a more even finish than fast swipes.
Step 4: Get Creative
Also go for as big a sample of oranges as you can. The set pictured in this instructable wasn't so large (had a cold and ate most of them before finishing :P) but you can sort of get the idea. A big bowl of oranges, each with an individually unique face makes for a great amount of fun.