Halacha Yomit is currently discussing the laws of Shemittat Kesafim (loans being automatically erased at the end of the Shemitta year) and Prozbol (the document that was instituted to not erase them).
At the end of each Halacha, there's a message with a link to a page with a form you can fill out to have your Prozbol done for you.
Translated, the message says:
Optimally, it is much better that each man will worry for himself to write a Prozbol as is proper according to the Jewish religion. However, for the needs of those for whom such a thing would be hard to do, and on the basis of a halachic decision of Maran Rabbeinu Hagadol Shlit"a [Rav Ovadia Yosef, Shlit"a], we are allowing - by way of the Halacha Yomit website - that anyone can sign their name and personal information for the purpose of appointing the rabbi who writes the halachot on the website as an agent - so that he will write a Prozbol for them.