I had someone ask me recently if I thought it was appropriate for ladies to "friend" men on Facebook. In an age when virtual relationships sometimes turn into real adultery, I think that's a very good question.
I answered that Facebook is a virtual community. Since I am friends with both men and women in my real communities, I have no problem "friending" men on Facebook. The problem arises when the relationship becomes more than a friendship. Now, that may be good or bad, depending on the relationship, such as in the case of our Sam and his new bride, Hannah. :)
I would liken Wall chatting to standing in the vestibule at church having a publicly viewable conversation. The chances of things getting personal are highly unlikely. However, Chat chatting is private and can become dangerous. This form of communication is more like talking with a male friend in a room with the door locked. There is no way anyone can even chance to come through. When I first got on Facebook, I was approached for a Chat session with a male friend I knew from college. Though our conversation was innocent to the best of my knowledge, it just didn't "feel" right. It may be necessary, as I found, to shut off the Chat feature on your Facebook account.
Facebook email can become personal, but is usually more like a letter, a card, or phone call. Sometimes this type of communication with male friends is absolutely appropriate. For instance, a friend on Facebook who has always been like an older brother to me wrote to let me know about a missionary couple I went to school with who were battling cancer. He is very, very close to our family and has also written to ask about my little sister's father when he passed away not long ago. These types of communication between men and women would not be inappropriate in any case.
It is important, however, to keep in mind that, unless you block them, Facebook email can come from ANYONE on Facebook. Unfortunately, our daughter had to block a male "friend" who kept sending unsolicited "encouragement." It was more than the attention she would have allowed in her public life, so she wisely determined it was necessary to stop the unwanted attention in her virtual community as well.
Just as in our real communities, we must exercise discernment when a relationship is going beyond the bounds of decency and appropriateness. Therefore, it may never be appropriate to "friend" some men, such as an old flame or an ex-spouse. Yet, even then, it may be appropriate depending on what that relationship would be in person.
My conclusion would be to try to determine whether or not you would be "friends" with this person in the physical world, and then to monitor that virtual relationship accordingly once you have accepted their Friend Request. And, as in any situation, you have to know when it's time to let some "friend"-ships go.