Ahah, I like this idea for a topic. It's something I've not seen before in my days spent on forums. Nostalgia really is one of my favorite emotions.
Anyways, I'm always going to remember doing strange sidequests before actually beginning or continuing with the main story (Whichever the case may be at the time). In the first several minutes of the game, I remember going around town and finding that the shop sold shields but not swords. I ran around in the grass until I had enough rupees, then bought one and wondered where the sword was. Then I eventually found it, and both of these were completely separate and happened before Mido told me I needed a shield and a sword.
Also, a few moments after I became an adult, I pondered what crazy nonsense would happen if I went to find my grownup friends in the forest (Not knowing that they didn't grow up) and while looking for Saria ended up accidentally finding the guy you give the chicken to and did the entire Biggoron's sword quest before even doing the Forest Temple, then found out it was completely optional. I always used that sword though. I even sort of missed it in TP. T-T