Many utilities have developed wind projects in the Midwest:

Great River Energy
Madison Gas & Electric Wind Power Program
Moorhead Public Service
Southern Minnesota Municipal Power Agency (SMMPA)
Waverly Light and Power - Iowa Energy Tags
Xcel Energy

Note: This list is by no means exhaustive and should not be seen as an endorsement of any particular utility

For more information:
Minnesota Environmental Quality Board: Lists current wind power projects proposed for a site permit and projects recently permitted in Minnesota
Green Pricing Programs: A list of utilities that offer green pricing programs to their customers throughout the US. It includes links to news releases and home pages of utilities.
AWEA's Project Page: Lists wind projects throughout the US