Write a postcard addressed to yourself with the correct address. Pretend it's from a girl you met and write that she just saw your posting at LPSG.org and your username. Have it be fairly obvious but not crude because nobody would be so public on a postcard. Then deposit it in your neighbors mailbox after the mailman comes so it looks like a mistake was made. Guarantee, if it is written well, their curiosity will get the better of them and they'll check out your photos.
If they're smiling at you next time you see them, then you know it worked.