Here are a few websites that post their turbine performance data:

Minnkota Power Cooperative of North Dakota: http://www.minnkota.com (see the Infinity Wind Energy links on the left).

Waverly Light and Power of Iowa: http://wlp.waverlyia.com/search_wind.asp

Also, Carleton College is planning to post data from their new NM82 at www.carleton.edu.
Does anybody else know of other good sources?

Missouri River Energy posts the output of their Riverwinds turbines at
http://www.riverwinds.biz/windinfo/

Eldora-New Providence Schools also posts their turbine production data:

http://www.eldora-np.k12.ia.us/enpdistrict/index.html

and shows how well the turbine is preforming in relation to the yearly loan payments the district pays on the turbine.

Look for the "Wind Turbine" link on the left.

The Wind Turbine Verifcation Program is another good place to get production info. Check out the Turbine Verification New Bulletin:

Older Issues: http://www.epri.com/targetNewsletters.asp?program=221745&value=01T084.2

Newer Issues: http://www.nrel.gov/wind/working_comm.html