Custom fields extended use

Hi
I want to create custom fields – i can do this with a custom fields plugin, but the problem is i want to keep it independent/disconnected from the posts/pages/etc. Currently, custom fields are attached with post/page which i dont want.

What I am trying to do is:
I want to save some data for example state, city and other information in the database using custom fields (typical fields are going to be state,city,zip,url). I may use this data later on a page to show it to users where they can select their city/state and the filtered information is displayed to them.

First of all, I want to provide the interface to admin wherein he can see the list of these fields as we see typical list of posts on the “posts” admin interface. Then admin adds, edits, deletes, etc to this list.

A typical example is html snippet. where in we create independent snippets and it allows the functionality to view in list, edit, delete or use its display code on pages.

Any ideas? Please let me know for any questions.