I'll join the 9/11 meme.
First, the politics: I can't believe we are where we are right now. In a war in Iraq, with strained relationships with Iran and North Korea (axis of evil), and pretty much ignoring the other country we invaded (Afghanistan). The world used to side with us, and we've lost that political/moral clout, and are now just the big bully on the planet. sigh...
Five years ago today, Mary and I were on our honeymoon in Greece. I believe we were on the island of Naxos. I remember looking around this little shop - they made cheese that was stored in tall/skinny baskets (I bought two baskets - no cheese). They had a little 12" TV (ok, it was probably metric, 30cm) that was alternating showing two smoking buildings and 4 people gabbing away in Greek. I remember thinking, "wow, someone's pissed." Little did I know.
We later sat at a cafe and had drinks, watching CNN.
When talking with other people we ran into, people from other countries seemed sorry, but they had the undercurrent feeling, "it has been happening to the rest of us for years now, it's your turn."
We certainly haven't behaved any better since the attacks, and I'd (sadly) be willing to bet that there are more folks now than ever that would love to fly another plane into some of our buildings.