When we first open a lending program in a new country, a local volunteer or visiting international intern typically finds an initial group of borrowers by making presentations at NGOs, pitching Zidisha to local cybercafe owners, etc. After that, growth happens almost exclusively by word of mouth.
Most in-country volunteers (we call them "Volunteer Mentors") are also Zidisha borrowers. They learn about the mentoring program via a note in the borrower account interface of our website, and apply via email.