The state of Iowa has a web site where you can donate to the relief effort.

Patrick Thornburg reports that:

The flood water has dropped but is still above the highways.  Some highways have had their bases washed away so it will take a long time to repair them.  I’ll head down this weekend and have a look.  The normal 75 mile trip (one-way) will be 140 miles because of the water and closed roads.

More video of the devastation.