I love Python comprehensions. I want to dislike Python - significant whitespace, weak lambdas, other trivial complaints - but the comprehensions are so nice, especially combined with yield and the iteration protocol, that it's usually the first language I turn to. There's syntax for sets, dicts, and generators too:

    >>> { char.upper() for char in "hello" }
    set(['H', 'E', 'L', 'O'])
    >>> { char: ord(char) for char in "world" }
    {'d': 100, 'r': 114, 'o': 111, 'w': 119, 'l': 108}
    >>> (char for char in "foobar").next()
    'f'