I've had some experiences using aikido without knowing it. Also, I try to use it everyday.
1. Playing soccer, I was chasing the ball with an opponent. He was bigger than me and managed to trip me up. Without realizing what I was doing I tucked into a roll and came up without missing a beat. What a great feeling.
2. This past christmas I was up snowmobiling in the mountains with my brother-in-law and sisters. I was on top of this little hill and thought I'd go and meet up with my family. As I started going down, it dropped out from under me. I had time to think 'I'm in freefall. Oh crap!' and then I hit the ground. My feet had been tucked up into the warmers, and I flipped over the front of the snowmobile. As I started into the fall, I followed my training instinctively and relaxed. Needless to say, I pulled all the muscles in my legs, but if I hadn't relaxed I could have broken my legs or even torn ligaments/muscles. When I landed it was flat on my back, but my arms came out to slap the snow and dissipate the energy. Although I hurt like hell for the next several weeks, I was proud of my aikido.
3. I use aikido in all my schoolwork. Using the mindset to deal with all my homework, projects, exams, etc. It's a timing and blending thing. Heh heh.
4. Whenever I open doors. Push doors I put my arm out, 'extend ki' (no Tyrannasaurus Rex!), and move from my center. Pull doors I hold on to the handle and do a little funikogi undo (sp?).