Check Classifieds at www.gulf-times.com for up-to-date housing rentals and rental agents.

Here's some example rental agency websites for some pics, etc. These sites were helpful to me before moving here.

http://www.zukhrof.com/

http://www.homes2rent.biz/Serviced%20Apartments.htm

http://www.mirageproperty.com/

Here's some more guides with general Qatar info for you:

http://hr.web.cmu.edu/forms/benefits/qatar/practicalguide.pdf

http://www.qp.com.qa/qp.nsf/web/living?OpenDocument

P.S. with regard to Al-Asmakh: opinions always vary, but my luck with them has been quite sour. Long story...