I used to ask questions like “where were you when…” in order to determine a girl’s age to see whether or not I could date her. Too young=creepy. Too old (or just old enough) = possible adventure. 
Elvis’ death: I was next door at my best friend’s house having a sleepover. We were wee lads, staying up late, watching Project Terror, the local late-night cheesy Friday night horror flick. They broke into the show to announce his death. I was mad because we didn’t get to see the end of the Lizzie Borden flick.
The Challenger Explosion: I was in my sophomore year digging through the shelves at the college bookstore. Somebody came in and shouted the news, then bolted out the door. I didn’t take it seriously, but did manage to pay for my books and wander over to the student union where everybody was glued to the TV. Classes were cancelled for the rest of the day.
The Fall of Communism: (Don’t think this has been mentioned yet) I was stationed in Germany. Our Commander held a formation and didn’t tell us what was happening, but he gave us **DIRECT ORDERS **not to cross borders out of Western Germany, due to military actions and what not. Once my buddy and I found out what was going on, we booked a flight the next day on a civilian German flight straight to Berlin to go see it for ourselves. Got some great pictures. One of the locals even gave me a sledgehammer and let me take a few whacks at the wall. I still have the pieces and the pictures.
Desert Storm: I was in college, enrolled in ROTC. My plans were to graduate, go to med school and then return to active duty Army as a doctor. I had a contract with the Army, had been (tentatively) accepted to med school and everything, given that I could graduate. When the US launched their invasion, my primary ROTC instructor pulled all of us aside and said that all bets were off, as far as scholarship students and contracts that were already signed, based upon “the needs of the Army”. The justification was that “War superseded all previous agreements”. So I was assigned to the Field Artillery instead of the Army Medical Corps. At least they let me graduate college first.
Kurt Cobain’s Suicide: I happened to be stationed in WA state and had the day off, so I decided to go sightseeing around downtown Seattle. I was on 2nd street trying to find Sub-Pop records (the indie label) offices on that day. It was weird. The sky was overcast (natch), but the whole area had this kind of gloom and sadness to it. I didn’t find out what had happened until later that afternoon.
The OJ Chase: I had money on the NY Knicks game that night. We were on East Coast time, and the chase happened on the West Coast. The game wasn’t even at halftime yet, but the station cut the game and went to the live feed of the highway chase. I was ticked. I lost my bet, but couldn’t see why. Grrr. (That’s what I get for betting on the Knicks, eh?)
9/11: I didn’t really experience the whole event until around 1 PM EST. I opened my real estate office at 8 AM, as usual, and started upon my daily routine. We had no TV or radio in the office, and the sales team people never showed up until around noon anyway. Most mornings I was alone until at least 10 AM. My boss called the office shortly after the first plane struck the tower and asked “What are you doing at work?” My reply was, “It’s Tuesday. I always work on Tuesdays. Why?” She said something like “Don’t you know…Oh, my God…” and hung up. That was when the second plane struck. I thought she was just being silly and didn’t know anything was wrong until I went across the street to get lunch only to find that the doors to the Shopping Mall were locked. Then I went back to work and started looking at the internet and found out what had happened. Then it got real for me.
The Columbia Explosion: A bit of schaudenfreude here. My psycho live-in G/F and I were in the middle of a free-for-all screaming fight with the TV on in the background. They started showing footage of the event, and me, being from TX, caught interest, as it happened over the Dallas skies. I managed to get her to shut up enough so I could pay attention, and she managed to stop her insane attack enough to feel sympathy for the sadness of the event. So I caught a break, but I was still sad about it.
The DC Sniper: I lived in Silver Spring, MD at the time, and worked in Bethesda, MD. Close to the DC line. After Desert Storm, I always figured if it was your time, it was your time, so since they didn’t have any real profile of either the shooter or targets, I just went about my business as usual. I took the bus to work on a daily basis. Sometimes I was late. I usually took the route that the bus driver was shot to work. On that day, I was actually on time and took the bus as usual. If I had been late, I would have been on the same bus that the driver was shot. Once I found out, I had a moment of “cheating the devil” and decided to take the rest of the day off. (But I got a friend to pick me up from work and drive me home.)
The Virginia Tech Shootings: I worked in the DC/MD area. It was 8 AM, and my boss’s boss was yelling at me to find my boss, who hadn’t showed up yet for this uber-important meeting today. I started doing my usual – calls to the cell, calls to the home, texting, emailing, trying to figure out where he was, why wasn’t he answering and why he wasn’t at work. It was about a half hour later that somebody came by my desk and told me what was happening. That was when I made the connection that my boss had a daughter who was a junior at V. Tech and lived in the dorms. I stopped my attempts and told his boss what was going on. They cancelled the meeting. I felt like a jerk about the whole thing, but not as bad as my boss’ boss later on that week. (She turned out okay in the end, but it was still a scary event for all his family.)