Before leaving, create a contact card with your name, e-mail, phone number (if you wish) and travel blog URL. This makes exchanging information simple. I used a business card model and printed two hundred cards, which I distributed among the friends I made as I walked across northern Spain.
To reduce the weight, other pilgrims printed their contact information on paper and then cut them to size. I prefer the traditional cardboard (3.42″ x 1.93″) — it does not crumble like paper and weathers better.