Is there a way to add data to the contacts details page??

Is there a way to add data to the contacts details page??

I need to load data from my application database and bind it to some custom fields in the Contacts module.
I want to display HTML data into the some custom related list in the contact details page.
Cant even add an iframe to the custom related list??

Can u give me some examples of using custom functions in the custom related list section.There is not much info available about it.

Is it possible to add a custom button to any module ??

Please Advice