This is snippet of code solves the interesting (and specialized) problem of generating all permutations of a list. I hope you like recursion. For exmaple:

permute( [0,1,2] )

would return

[[0,1,2],[0,2,1],[1,0,2],[1,2,0],[2,0,1],[2,1,0]]

Builds and prints a list of all links in a specified webpage

Quick way to get the users home directory in Unix/Linux and Windows

Decompress a .tar.bz2 archive in Pytho

Computes the difference between two dates in seconds

Reads well formed RSS entries using standard python libraries

Reads a file line by line using Python in 3 lines

Very fast method for extracting all of the unique items from a list while preserving their original ordering.

Introduction
This function is a function that returns a function. You pass it a function, and it returns a function that takes a collection as a parameter and applies your function to it. The difference between this and map is that this returns a function that you can use again which takes a collection as a parameter.

For Example
If I had a collection c, and a function p that prints its argument, I can create a visitor function using the following:
printVisitor=createVisitor(p)

Then any time I want to print a collection I just type:
printVisitor(c)

A Better Example
If you were writing an IRC server you would probably have many functions that operated on a list of users, such as ban,makeop, etc. You could create those functions in a manor similar to the following:

banUsers=createVisitor(ban)
makeOperators=createVisitor(makeop)

Then in a seperate file you could use these functions as if they were regular functions.

you would type banUsers(users) to ban, or makeOperators(users) to promote those users.

Translates text from using translate.google.com