Add space to, swap Lastname,Firstname

Before I reinvent the wheel: Is there a known way to do something like the reverse, to change a field with, say, "John Coltrane" to "Coltrane, John" by swapping the words and placing a comma after the one moved to the first position? I do this a lot by hand (and realize that I would have to look at the contents before doing it to avoid messing up "Jethro Tull").