While I have gotten used to seeing boys' names used for girls (not that it is a trend I enjoy), we usually don't see trends of the opposite. I think Memphis is one exception that I have seen in the birth announcements for boys and it even made it to #923 on the popularity charts for boys in 2006. Memphis was a female name from Greek mythology and I would bet that most are just naming after the city. I wonder if parents would still use it for boys if they knew the real origins. Thoughts?
Here's some sources about the name:
http://www.ancientlibrary.com/smith-bio/2137.html
http://www.theoi.com/Nymphe/NympheMemphis.html