There is a "Guest" flag, but I believe that technically means that the boat owner is not present and the boat is commanded by a "guest".Is there some flag you can fly on your boat that indicates that you are open for visitors?
or is there a high tech version of that?
I would expect a lot of sailors wouldn't even know what it means anyway...
Something like this might be more universally recognized as "we are social"... ;-)
You could also fly something related to a topic that is controversial or that interests you and attract folks that find that topic interesting.
There are also places you can get an nice custom flag or pennant made up and put up your own more direct message: "Visiting hours: 9:00 AM - 11:00 AM"
Maybe do something like put scantily clad blow up dolls or manikins on your deck to indicate a fun party? Depends a lot upon the visitors you are trying to attract. jajaja. Hmmm... also maybe a good idea for those worried about putting their boat name on the dinghy? A manikin in security guard outfit?