I pass on a warning which was published in a local newspaper about
collectors of business cards. The scam  may be the use of the cards
to solicit business of a less than legal kind. I can't remember the details
except that the scam involved the use of legitimate business names and
addresses by the card collectors for illegal purposes, or if not illegal,
for obtaining mailing lists for other than the purposes stated by the
collectors. I sent off a pack of business cards to Craig Shergold quite
some time ago, and hope that I haven't caused a problem by doing so.
I have had two or three similar sorts of business card requests, one
by a chain letter. I don't know which are legitimate and which aren't.