Nama Hatta - means the Marketplace (hatta) of the Holy Names (nama) of God. In the context of ISKCON, nama hattas are small, local Hare Krishna groups, where persons come together meeting regularly to chant Hare Krishna (kirtana), discuss Krishna consciousness and share prasadam.
The name itself comes from a marketplace founded "in the 1500's in West Bengal by Sri Nityananada Rama on the Island of Godruma in Navadvipa. Based on the principle that the price for chanting purely the Names of God is sincere faith. With however much faith one possesses, that much benefit can be derived from the chanting. One does not need to leave his(her) home, family or position in life. One needs only to come to the market, buy what one desires and take it home. Thus Nama Hatta is for teaching the world to advance spiritually at home. It does not require extraneous endeavor or great investments of money. Any place where one can easily obtain the mercy of receiving the pure Holy Names of God to chant is a part of the Nama Hatta."(*)
(*) Explanation from Atlanta's nama hatta.