Salt
I did not see any real significance behind why her name is "Salt" - other than it is her last name. I know there have been some people speculating on theories about this, but there really is no significance to it other than it is her "code name" - a last name that she was given.
This is an excellent film. There was a very good balance between action / adventure with enough "downtime" for story development and plot manipulation. Even if you do not like action/adventure/spy movies, this movie is a must see. Wthout giving anything else away, it is a must see because I thought it engages the audience, makes you think that something like this COULD happen (not saying it would) - and up until the very end you are just guessing whose side people are on.
Wonderful film - definitely worth the money to see it.