But it had to be special...
Step 1: The Paper.
The thinnest, lightest paper I know is cigarette paper.
You need one paper for one aeroplane.
Disclaimer: I do not smoke. I do not recommend you smoke. Really. It's bad. And expensive.
However, for only 23p (about half a dollar) you can buy a packet of fifty cigarette papers - that's a lot of 'planes.
Step 2: The First Fold.
You can slightly dampen the glue to hold the paper in place. Not too damp, or it goes wrinkly and sticks to your lip. That's not pleasant.
Step 3: Down the Middle
This edge will become the front of the 'plane.
Sharply crease the 'plane down the centre and then open it up again.
Step 4: Shaping the Front.
You should see a crease that was already in the paper when you got it. It forms a V, with the point at the front of the plane.
Fold the two front corners up to meet the pre-existing crease. The crease that was at the front edge should line up along the crease that makes the V.
You now have a point at the front of the 'plane.
Fold this point up to approximately the centre of the 'plane.
Step 5: The Body and Wings.
About 3mm from the centre crease, fold both sides down to make the wings.
The 'plane should start to look just like a 'plane now.
Fold the tips of the wings upwards for stability.
The larger the wing-tips you fold up, the straighter the plane will fly, but the smaller they are the longer it stays in the air. It's up to you.
Step 6: Flight.
There is one thing you never do with this plane, and that's throw it.
You gently launch it, or even just drop it, but you never throw it. It simply won't work.
The best way to fly the 'plane is to hold it by the very back of the body, 'twixt finger-tip and thumb-tip, hold it as high as you can, and drop it with a gentle push forwards.
The plane will then drift earthwards, sometimes in a gentle spiral.
Because of the small size, tiny differences in creasing have quite dramatic effects, so every one of these i have made has flown differently at first.
To alter the flight, gently adjust one or both of the wing-tips - either lay it out flatter, stand it up straighter, or give it a slight twist.
When you're happy, take it somewhere high to fly it - from the balcony of a theatre, from the choir stalls of a church, or from the upper levels of a mall. Or take it to a castle and see if you can fly it down a spiral stair-case.
I did try and video mine in flight, but failed miserably - they're just too small to catch with my camera.
I ought to add that this is not mine design, but came from a ragged old book I got second hand, called Paper Airplanes.
Edit, 2015: It turns out that the book is still available, and was written by a fellow Brit called Nick Robonson! Have a look at the author's site here: LINK.