Didn't see this posted and this would be good for people coming in from out of town.
New for 2013 is Welcoming Our Wolverines (W.O.W.) Fridays. There will be a member of Guest Services located in front of Gate 10 on Fridays before home games. The biggest attraction is for a $10 fee, you can tour Michigan Stadium and Crisler Center.
http://www.mgoblue.com/facilities/stadium-changes.html (bottom of the page)
EDIT: difference from the tours offered through the Alumni Association is they are much more detailed. You also get to walk the tunnel, actually get on the field, visit the locker room, visit the Jack Roth Stadium Club, see the Heisman Trophy and try on a helmet/pads. The $10 Fri tour only says you will have an opportunity to take pics inside the stadium. http://alumni.umich.edu/connect/event/big-house-tours