Actually there were two Ann's:
Ann Arbor was founded in 1824 by land speculators John Allen and Elisha Walker Rumsey. On May 25, 1824, the town plat was registered with Wayne County as "Annarbour;" this represents the earliest known use of the town's name.[10] Allen and Rumsey decided to name it for their wives, both named Ann, and for the stands of Bur Oak in the 640 acres (260 ha) of land they purchased for $800 from the federal government at $1.25 per acre.
also:
The local Ojibwa named the settlement kaw-goosh-kaw-nick, after the sound of Allen's sawmill
Ann Arbor is a unique and good name, but Kaw-goosh-kaw-nick would've been pretty sweet too.