I have the rarest of birthdays coming up (leap year) and was wondering how rare I am as a human being.  In addition to being born on February 29th, I also happen to be left handed, have B negative blood, and morton's toe. What are the odds that there is another person out there with these same characteristics?

Almost impossible to calculate. One would need to know the precise prevalence of each of the variables you mention within the specific population and I think it unlikely that information is known. You would also need to be sure that each variable is independent of each other.