I have one on my right hip that is in the outline of the continents Europe, Asia, and Australia. All connected too, well except for Australia, that one isn't connected but has "islands" leading down to it. Weird, I know, but completely true.
And one, I think it's a birthmark either that or it's a burn scar, shaped like one of Frankenstein's monster's scars on my right elbow.
My dad also said that I had a cross shaped one at on the top of my neck near the base of my head when I was a baby, but it went away.