Want to create module about variables editable by users - anything similiar already?

Hi.

I want to create module which allows users to modify variables chosen by admin.

Idea: I have created site for my client and want him to change some information on website, where I cannot allow him to access to code etc.

Example 1: I prepared block which use PHP Code and want client to have access to one text string change, but not for all PHP code.
Example 2: I have jquery code which sets default form value and want client to have access only to the default value change, not all of jquery code.

Solution:
1. Admin defines which variables user can edit and human readable label for them
2. User go to the page, where all allowed variables are displayed and can modify them.
3. Only users with specific permission can access the page, hence can modify vars.

I am aware of module drupal_variables existence but it:
1. Do not allow to define which vars can user edit
2. Do not allow to set human readable label, so it is not elegant way to edit vars by client.
3. Do not displays all variables in only one page.

Does any other module do something similar? Any ideas about features for this kind of module?

I attach the very start of this module development.