Without reading seven pages of replies (so I apologize if this has been brought up), I think at least a tattoo on the ring finger is in order for both men and women. If they get divorced, an X can be tattoo'd over the "married" mark.
I dated for over 20 years before I got married and it would have been nice to know for sure who was married and who wasn't.
Honestly, I never met so many liars and truth-stretchers than when I was dating. If they'd have had some kind of mark on their finger indicating their attachment, I wouldn't even have considered going out with them. And if they're divorced, then they wouldn't mind the X mark noting their availability to date again.
Of course, serial marriages WOULD potentially take a toll on that finger.
But it would let the new girl know that this man potentially has children he has to pay support for so she shouldn't expect any kind of lavish lifestyle from him until those kids are over 18. It would also let her know that this guy has been married X many times before and she might want to think twice before walking down the aisle with him.
A tattoo would solve the whole safety issue with men who work in dangerous jobs where they could lose a finger because of the ring.