What is a good technique to make leaves with? Or is there a script? Specifically, I need to make palm leaves.
Try the lsystem tree generater script, i belive the site its hosted at was called Blenderdungeon, search for that info on google, unless someone else has the address. You can make full on trees, but can also just extract one leaf from the mesh and delete the rest, good luck!!! 
Matt
Blend on, and blend well!!!
On the other hand that script is great for brancy trees with small leaves,
question here, if I’m right, is for a palm, which is a branchless tree with enormous leaves.
Let’s assume you have the trunk.
I’d model a single leaf with the accuracy you think you need.
I’d make a coarse tube (say exagonal) or half iconsphere, depends… and fract subd it twice
I’d parent leaf to tube, press Duplivert and Ot
I did this flowers (iconsphere base) http://www.selleri.org/Blender/images/dragonfly4b.jpg
with this method.
Stefano