I'm sorry, but I'm trying to figure out what exactly you mean by data retrieval and "public domain" and parsing directories and such.

The government has websites that are public domain. Data retrieval is done by going and getting the data with a program. then manipulating the data to fit your needs. (weather, tides, news releases, public announcements, etc...)

thanks, there is alot of healthcare data out there and I was just wondering how I would go about "pulling" this info.

first you need the site you want to pull from.
Then you use a stripping command to separate the various components and setup your arrays. Then use a regex (regular expression sort the results) ... Next comes formatting into what you want to have. Then a inclusion into your template.

Fishtails has a example of how one works with his tidecal in this forum. It is a very simple process if you can learn the code.. which is more difficult. I have to get help to do mine... but have the general idea of what I want done.