Use a list comprehension.
To get an array of the names:
names = [name for name, tag in person]
To output a string in the format you give:
# Python 2 (print is a statement)
print "\n".join([name for name, tag in person])
# Python 3 (print is a function)
print("\n".join([name for name, tag in person]))
This is really a basic Python data structure question - it's not specific to NLTK. You might find an introductory guide like An informal guide to Python useful.