First up: pre-season game vs. the Tennessee Titans at their place, Sat. Aug. 9, 7:00 PM Central.
(Incidentally, I found this site quite easily just by googling "apple calendar subscriptions". There are others as well. Pick the one that tickles yer fancy.)
Update: If you tried to use iCalShare to do likewise for the Wisconsin Badgers, you'd have been disappointed, as the most recent listing was for 2006. However, if you go to the Badgers' own website, you can follow the "Schedule" path to the destination
First up: Wisconsin vs. LSU in Houston, Sat. Aug. 30, 8:00 PM Central.
Note that a download (as for the Badgers) is a one-time-only deal. Once you've done it, it's done, and your Calendar listings won't change thereafter unless you consciously change them. A subscription (like the Packers), OTOH, can be dynamically updated by its original source.