Info and application link here: http://www.mgoblue.com/facilities/stadium-team.html
I've been an usher for the past three years, and it's a good time. It is a big amount of work and a huge time commitment for laughable pay, but getting to be there is worth it for me, and probably some of you... You have to show up 2-3 hours early for each game, and you will be standing the entire time. You will also miss large portions of the game, as you're there to work.
The athletic department hires every summer, to the best of my knowledge, because of the high employee turnover rate. A lot of people don't understand the time commitment part until they've spent three straight Saturdays standing in a crowd of 100,000 people for 8 hours. It's not for those who can't stand and be outside for that long... But I would recommend applying if you don't have season tickets and are willing to work a bit to fix that.