when i had my EP3 civic, sometimes i would see another EP3 somewhere, and i would leave a note under their wiper asking if they are a member of ephatch.com and i left my screen name.
i would have no beef with someone leaving a note on my car if it was something like that. though i'd immediately think the note was from someone that hit my car and left their contact info.

 

but if i had some cards, i could write my name and number on it and put it in the fish bowls at restaurants to win some free food. bonus.