Long post....
The win over OU in '07. Both teams made mistakes, but it was nice to see the Buffs being competitive with what ended up being the Big 12 Champ. No one saw it coming, even in a year of upsets.
The 30-6 over TT in '06. Seriously, the team did not want to go down as the worst Buff team in history (even though they tied the losing streak) and TT had no shot at all. The student section, for the most part, failed to show up, but those that did were the rabid, diehard fans that represent the university well even to this day. Utter domination of a good team in a really down year.
When I graduated in Folsom in May '07. I had actually graduated that December, but due to the blizzard of '06 I was able to walk with my friends in May. Turned out to be a major blessing. I flew out my parents since they couldn't afford to fly out themselves and showed them around Boulder and the university. My parents had always felt bad that they couldn't send me to the school of my choice for ugrad, but I had managed to get grad school paid for by my company and I chose CU over others. My parents were really proud of me and, especially my mom, loved that I was able to attend a school that I had a strong desire to attend. Ugrad was very difficult for me, especially socially, and things at CU were a 180 degree turnaround (my parents adored my friends as well).
The CSU game in '07. I didn't get to attend the game at all, but it's the story, not the end result. My mom had a heart attack the week before and was recovering from minor surgery the week of the game. I had seen her in the hospital and called her everyday to see when she was going to be released from the hospital. She was released the day before the game and I called her to ask her how to make breakfast burritos (her specialty). My aunt later told me that she appreciated the call and just the idea that I always needed her. At 6am the next day I received a call from my Dad that she had had another heart attack and was in a coma. My good friend drove me to the airport, I somehow made it to El Paso and my brother picked me up from the airport (about 45 minutes away from home). I was at her bedside when my friends all sent me a text message that CU had won the game and that the burritos I had made the night before were great. My mother died 19 days later.
So my proudest moments don't stem from necessarily having an awesome football team (although it certainly helps), but when I realize how much CU meant and still means to me. My friends, the memories, the studying, the partying, the late nights, the stress, the relief, meeting new people (both good and assholes) and trying new things. Even when things seem bad, nothing could take away the experience I had at CU...and that's why I'll always be proud to be a Buff.