Calculating distance between two points, finding zip codes/cities, etc. (US cities only)

[eluser]taewoo[/eluser]
Hi everyone.
This is my real "contribution" to CI community. So excited!

A long time ago, I developed SpeedyWord.com (a site dedicated to helping people find local, trustworthy service based professionals like car mechanics and nannies) using Micah Carrick's PHP Zip Code Range and Distance Calculation script. It's an awesome script.

Since i'm doing a lot of CI work now, I figured I might as well port this. If you're developing a locale-based service web app, this is really cool tool.

Steps
==========
1) Download the zip file from the site
2) Load your MySQL database with the .sql files (as instructed in the zip file)
3) Put the plugin (see attached) into plugin directory
4) Put the model (see attached) into model directory
5) In your page controller, do

Code:

$this->load->plugin('zipcode');
$z = new Zipcode();