Tough to put in order but have seen some great shows:
-Dave Matthews Band (with unnanounced special guest Neil Young), Ben Harper, Jack Johnson as openers, evidently My Morning Jacket opened also - Vote for Change Tour, Hilton, Ames IA, 2004
-Billy Corgan - solo acoustic (only show that I know of) - Metro, Chicago 2004
-John Mayer - Schubas, Chicago, unnanounced until a few hours before the show and had a buddy that worked at this ~200 capacity bar that got me in
-Tom Petty (with Stevie Nicks) - Bonnaroo 2005?
-Black Crowes, Jack Johnson, O.A.R. - Bonnaroo 2004, all were playing at the same time and caught bits of all three great shows within two hours
-Roger Clyne & the Peacemakers - anywhere - one of the best live shows you will ever see
-Coldplay - UIC Pavillion, Chicago 2003 - right before they got really big
-U2 - Target Center, Minneapolis 2001 - Elevation Tour, this show was during finals week. My buddy picked me up immediately after a 4pm final, drove straight to the show from Ames, watched the show, drove right back, got back around 5:30 am, stayed up until 9 am to take my next final. AND made Dean's List.
-Greyboy AllStars - Aggie Theatre, Fort Collins CO 2009
-White Stripes and Flaming Lips - Aragon Ballroom, Chicago - New Year's Eve - clips from this show are on the Flaming Lips documentary
Interesting side topic: shows that you could have easily gone to, but didn't for some stupid reason
-My Morning Jacket, Red Rocks 2008 - heard was an epic show, had just moved to CO and was pinching pennies
-James Brown - Harrah's Stir Cove, Council Bluffs 2007? - This show was about a month before Mr. Brown passed away, one I never got to see
-The Nadas final show @ Peoples - I was fishing in Canada with my grandfather, so I made the right choice, but it was tough to miss that one
This would be VERY high on my list...
Other great shows I've seen
-Ben Harper & the Innocent Criminals, Ames 2003. Jack Johnson opened, as this was before he was a mega star, and it was an all around great show.
-Rage Against the Machine, Alpine Valley 2007. Queens of the Stone Age opened, but I was really hammered during their set. Rage absolutely rocked the place. 60,000 people screaming "**** you, I won't do what you tell me!" was insane.
-Drive-By Truckers, Omaha 2008. We were right up front and they played an absolutely amazing set, just completely kicked ***. The Felice Brothers opened, and they are also a great live band.
-O.A.R., Ames 2005. I'm no longer much of an O.A.R fan, but this was before the All Sides album (which sucks), and they were on their game at this point in time. We had also spanked K-State earlier that day, so it was an all day party full of tailgating, good football, and good music.
-RHCP, St. Paul 2006. They played a great show, with a stunning encore (I Could Have Lied and Give It Away).
-Drive-By Truckers, Iowa City 2007. We could steal Patterson Hood's Jack Daniels, we were so close. Got picks after the show and shook hands w/the band.
-80/35, Des Moines 2008. What a line up last year! Flaming Lips, the Roots, Drive-By Truckers, and others just tore it up.
-DMB, Alpine Valley 2005. O.A.R. opened both nights, and the DMB played great set lists both nights. Final song of the sunday night set was Two Step, my favorite DMB tune.
-Various bands @ People's. It was always fun going to Damon Dotson, K-Top, etc at People's. Good music, good brew, and always good scenery.
-Fork In The Road, Logan IA 2008. Great bar band playing their home bar the night before Thanksgiving. If you like southern rock, classic rock, blues or classic country, check these guys out.