I was at Debconf 2 in July 2002, and it was really cool. I attended Damian Conway's Perl talks, and I've typed some stuff up from my experiences.
I went to the first annual FSF Associate Membership meeting in Cambridge, MA with my friend Jim Morrison. We had a good time down there, and also an interesting trip.
I also attended the first GCC Summit. Most memorably, we got together for a big keysigning party.
I then got addicted to conferences, so in 2004 I went to the second GCC Summit and then the 2004 Ottawa Linux Symposium.
In 2005, I continued this trend by going to the third GCC Summit. I will be attending the second Desktop Con as well as the 2005 Ottawa Linux Symposium.