to pumpkin-light my skull, I used the Throwie formula (search "throwie" on youtube and you'll find tons of vids and a few tut's on making them)
Here's a no brain simple LED you all can use. No soldering, no resisters or anything.
All you need is a CR2032 Lithium battery (can buy at any jewelry counter at stores like wal-mart and such. I got a 5 pack for under $4 off Amazon), a 10mm LED light (I bought a pack of 100 of them for under $6 on ebay), some paper and tape.
Here's a pic of the part list...
I cut one piece of card stock paper (like an index card) in a square to roughly fit the battery and another as a thin long strip.
Notice that the LED wires has one short and one long one. The short is negative and the long one is positive.
Place the wires of the LED onto the battery with the short wire on the neg side of the battery and long one on the positive side (the side with the wording on it is the pos side. It will have a + on it). The LED will light up.
Place your long strip of paper under the negative wire between it and the battery. This will cut off the circut and turn the light off...
Then place the square paper over it...
While keeping the pieces of paper in place, wrap a piece of tape around the whole thing (battery, paper and wires)
When you pull the long slip of paper out, it turns the light on. You can place it back in to turn it off.
And there you have it. A simple LED to make your icky things glow
This is what I'm using to light my blucky demon head.