There is a Chassidic custom to regard the fifth night of Chanukah as special. It is the first night when most of the lights are lit. A more technical version of this point is that it is the first night when following the opinion of Beis Hillel to start with one candle and add one every night results in more flames than following the opinion of Beis Shammai (to light all the flames on the first night and take one away each day). The fifth night of Chanukah can never fall on Shabbos, which might be regarded as something negative, but one way of looking at it is this: The light of Chanukah can even overcome the darkness of never falling on Shabbos. One of my favorite stories about the Lubavitcher Rebbe includes this thought. Read it here. Another story about the fifth night is here.
Tags: Chanukah, Chabad