Years ago, in Miami, I knew a Haitian woman who practiced Santaria (sp?) and she claimed that I gave her good luck (not sure why to this day). She called me her "good mojo" (ala Voodoo), or just Mojo - and the nickname stuck. Many people I was aquainted with knew me for years and never knew my real name.
These days I move in a very different circle where the name might not be appreciated - but I still am Mojo to my close friends.
I use a number of variations as "usernames" on the internet.