During her 15 years as co-anchor of Today, Katie Couric had the bulk of the nation's morning-TV viewers focused on everything from her hard-hitting interviews to her latest hairstyle. We asked our PEOPLE.com readers to name their favorite moments—a breaking news story, an on-air blooper, a heartrending story—from her stint on Today. As she prepares to sign off May 31 (en route to becoming anchor of the CBS Evening News in the fall), Couric shared some behind-the-scenes scoops on our readers' picks.

As the tragic events of Sept. 11, 2001, unfolded, Couric and the Today show crew stayed on the air for an extra three hours to cover the breaking news.

That was one of the most shocking days of my life. I looked up at the TV monitor and saw CNN was airing a picture of the World Trade Center on fire. I thought [a pilot] had had a heart attack on a private plane and crashed into the tower. Only when I watched the second plane crash did I realize it was a terrorist plot. Irrationally, I thought, "At least it's before 9 a.m. and people aren't at work yet." But they were. I think it was my way of dealing with it. My hands were shaking like a leaf. Later, I was interviewing [NBC News chief Pentagon correspondent] Jim Miklaszewski, and he said there had been a big explosion at the Pentagon, and I thought, "What a weird coincidence." My children were in school and I felt that was a safe place, but my parents live near the Pentagon, so I called during a commercial and told them to go to the basement. And it was so terrifying when we heard about [Flight 93] in Shanksville, Penn. I literally thought the world was coming to an end. I was horrified, but I also knew that people were depending on me to tell them what was going on. I just tried to deliver the information in a calm, cohesive way.

Two days after the April 20, 1999, shooting spree at Columbine High School, Couric interviewed Michael Shoels, who had lost his 18-year-old son Isaiah, and Craig Scott, then 16, who had lost his sister Rachel, 17.

That was by far one of my most memorable interviews. The scene was so surreal because there was a late-spring snowfall against a pitch-black sky, and they were two very shell-shocked people. Craig had to play dead and watched his friends [including Isaiah] get shot, and he later found out his sister Rachel had been killed. Can you imagine? They were two incredibly damaged souls, and it was one of the most poignant 15 minutes of television I've ever experienced.

After the 2002 kidnapping of Elizabeth Smart from her parents' Salt Lake City home, Couric landed the first interview with the 15-year-old six months after her rescue on March 12, 2003.

Like so many Americans, I lived through the horror of that story. I was really nervous about seeing Elizabeth because I didn't want to exacerbate any trauma she had already experienced. It was a hard balance of wanting to ask her good questions but also being respectful of her privacy and healing. At this point in my career, when it comes to people who have gone through suffering, their well-being is more important to me than getting the interview.

On Feb. 24, 1998, Couric returned to Today, after taking about a month off to mourn the death of her husband, Jay Monahan.

My husband Jay's death [from colon cancer in 1998] made me aware of how many people are in pain and how many people are suffering every day. And, conversely, how grateful we all have to be when the people you love are healthy, because experiencing the opposite is an alternate universe. If I was able to be inspiring by getting up every morning, facing the world and trying to find joy in life, I feel so grateful to have been able to do that for someone.

After her husband's death, Couric helped raise awareness about colon cancer by having an on-camera colonoscopy that aired on March 7, 2000.

I was nervous! I'm not a big fan of needles, so that wasn't thrilling. But the segment had the potential to save lives. I think many more people have been screened because seeing how easy it was removed the mystique. My colon cancer work is by far my proudest professional accomplishment. To [hear] I've impacted people in a way that contributes to them living longer, healthier lives is incredible. Some people have sent me photos of their colons! Now that's what I call over-share!

During the 2002 Winter Olympics in Salt Lake City, Couric gave co-anchor Matt Lauer a less-than-smooth ride on a snowmobile.

In retrospect, that was hilarious, but at the time, it was a little scary to say the least! I couldn't really drive the snowmobile and I kept hitting the throttle when I meant to hit the brake! There were some pretty close calls, but we survived. Matt was slightly unnerved and told me all he could think about was how they would tell his wife and son if something terrible had happened.

Over the years, Couric had a series of memorable misadventures during Today's cooking segments.

Once I had to swing a bag of lettuce around to dry it, but I didn't realize the bag wasn't closed. I swung it around and pieces of lettuce went flying everywhere. Cooking is not necessarily my strong suit.

And then there was the time when one chef cut a live lobster in half on-air.

That was pretty awful. I had no idea the chef would do that and given the camera shot was right over the skillet I would say it was clearly unappetizing. I still eat lobster, though.

Couric and co. always went all-out during Today's annual Halloween celebration.

We all dread Halloween in the days leading up to it, but we end up having a great time. When I dressed up as Peter Pan [in 1999], flying over the audience was really fun. I got to practice flying around Rockefeller Plaza the day before, but I didn't rehearse with the understanding that people would be there the next day. So that's why I [accidentally] slapped some guy in the head with my slipper on the day of the show. And the year I was Donald Trump [in 2004], I knew he was going to come by the show. I happen to love the guy, but the most dangerous place in the world is between Donald Trump and the camera.

Couric made an impression by not only being willing to experiment with hairstyles but also by often revealing how her mother felt about her new looks.

I can't believe some of the photos from the past. There's a method to my hair madness which is: I went lighter as I got grayer because you don't have to dye it as often. I'm actually pretty gray. My best look? I don't know. Clearly not the time I cut my hair like Winona Ryder—one inch all over the place—that was really bad. I think my hair looks better when it's sort of to my shoulders but not too long. Every time it gets too long, my mom calls me and says, "You really need a haircut." She keeps my hair in line. And she'll say, "That outfit you were wearing? Was it supposed to look all wrinkled?"