The competition to get a big-name commencement speaker is fierce among colleges each spring. From past-due favors to large sums of money, here’s how campuses landed the marquee speakers:

The University of Oklahoma has had Arlington nativeKatie Couric on its graduation-speaker wish list for four years. When the commencement committee asked Couric to speak to the Class of ’05, she declined but agreed to speak this year. Though Couric and the university’s president, former senator David Boren, are acquaintances, Couric was contacted through a speakers bureau. And after CBS paid an estimated $15 million for Couric, the $115,000 she got for the speech could be considered a steal. What did cross-state rival Oklahoma State University do to one-up Couric? It secured one of the three college speeches by commencement speaker in chief George W. Bush.

Back when George H.W. Bush was president, George Washington University’s Steve Trachtenberg invited him to speak at the 1991 commencement, but Bush declined. Fast-forward 15 years: The former president called Trachtenberg regarding a late recommendation he sent in for a student applying to GW. While Trachtenberg had Bush on the phone, he figured he’d see if Bush could be the 2006 commencement speaker. Bush said yes and agreed to bring along wifeBarbara to speak; both also received honorary degrees. Other honorary degrees went to Nationals manager Frank Robinson and motion-picture association chief Dan Glickman. Glickman, the only GW alum in the bunch, delivered the keynote address to the law school.

So if it takes 15 years to get a former president to speak, what does it take to get two former presidents to speak at the same time? The answer is Walter Isaacson, president of the Aspen Institute and trustee of Tulane University. Isaacson is friendly with both George H.W. Bush and Bill Clinton and lined up the pair, who headed a Hurricane Katrina relief drive, to give a ten-minute speech each, free of charge, at the university’s first commencement since Katrina hit.

CNN’s Wolf Blitzer was indebted to Catholic University president Reverend David M. O’Connell. During the papal transition last year, Father O’Connell was a guest on Blitzer’s show ten times. O’Connell turned around and asked Blitzer to speak to Catholic’s graduates this year.