You might be interested in the Open Knowledge Foundation's project on Public Domain Calculators (PD Calculators), which is a project to build software to help calculate copyright term in each country.
If you really want to place it in the public domain, you should use a legal tool to do so. It's not clear in every country that you can indeed dedicate work to the public domain, so a joint PD dedication and license is required.
Public Domain Calculators
You might be interested in the Open Knowledge Foundation's project on Public Domain Calculators (PD Calculators), which is a project to build software to help calculate copyright term in each country.
http://wiki.okfn.org/PublicDomainCalculators
and video at:
http://www.vimeo.com/15678944
All of this so that we can see the value of the public domain and help people use the PD work that is out there.
Public domain dedications require legal documents
If you really want to place it in the public domain, you should use a legal tool to do so. It's not clear in every country that you can indeed dedicate work to the public domain, so a joint PD dedication and license is required.
You can use Creative Commons CC0 to do so, available through their license chooser and directly at http://creativecommons.org/publicdomain/zero/1.0/
For databases, you can use the PDDL by Open Data Commons http://www.opendatacommons.org/licenses/pddl/
Putting an IP notice on the footer of your page explaining your license terms would help cut down on these requests.
Thanks!