I always print up a few business cards with pertinent info (name, e-mail, fax etc.) on the computer before I leave.
I give them out to people in comfortable social situations and I am amazed at the response I receive. I get e-mails and faxes (via efax.com). I get scanned/digital pictures of myself with the newfound friends I have made in Europe, along with much appreciated personal messages. I have gone on to visit many of my new friends on other visits to The Continent.
I am currently corresponding with many people, including a Cuban/American widow on a pension, two Madrid university botany lab workers, an American ex-pat who is teaching english, a vice president of a major pharmaceutical company who lives in Moscow, a Swedish gym teacher (it's not like it sounds!) and the "novia" of one of my best friends. (He doesn't have e-mail).
They invariably all start out with "I came across your card today"!
Give it a try!