whats_this_do.js

// what does this do?:

(function(){
    var i = 5;
}());


// What this does is create an anonymous function then assigns a local variable 'i' 
// with an integer value of 5 to it. Then it runs the function.

(function(){}); // creation of anonymous function
(function(){}()); // creation of anonymous function which is then ran.


// is it like a javascript hack equivalent to the jQuery(document).ready()? e.g.:

$(function() { 
    var i = 5; 
});

// $(); is short-code for jQuery(document).ready(); Some use this for it's shortness,
// but it doesn't give you a no-conflict use of the $ character. This may problems
// if your project uses prototype or any other javascript library that uses $.
// Good reference: http://api.jquery.com/ready/

Hey, thanks Karbassi! You kind of failed to answer my question, but that is entirely my fault - I failed to ask you the right question. But you gave me the stuff I needed to hit up Google successfully this time. Here is what I meant to ask, and some good answers:
http://stackoverflow.com/questions/1643321/javascript-why-the-anonymous-function-wrapper

PS
then assigns a local variable 'i' with an integer value of 5 to it.

Wow, you are either very verbose, or think I'm a complete javascript n00b. Knowing you, I'm entirely sure it is the verbosity. ^_^