Seattle-based Zillow said last night that it has acquired Mortech, a Lincoln, Nebraska developer of software tools for the mortgage industry. Zillow said it paid $12M in cash and 150,000 shares of its stock for Mortech. Mortech has 39 employees and was founded in 1987. Zillow said the buy would help it expand its professional services offerings to its Zillow Mortgage Marketplace. Zillow said the buy is its fifth in two years, and the first in the mortgage area.