We've just put up a Beta of a new easy online database tool that supports relational database web apps (Master / Detail records).
It sounds like it would be a good fit for a simple contact database (though not sure that you need master/detail tables - perhaps just a contacts table).
The site is http://www.rhythmdata.com.
All you need to do is tell it the names of the fields you want to collect and it generates the forms and sub-forms for you. There is no need to design the forms.
The Beta currently only runs in Firefox, but we're working on adding support for the other browsers now.
We would appreciate any feedback that anyone has to offer on our system.