The first night at a friend who just got his A500, the ease with which we could run software. Games of course (I remember Barbarian/Psygnosis), and I discovered there were teenagers just like us forming groups and being creative!
I had been a member of newsletter clubs and similar before, and also swapped disks with friends, but this was something new. A big movement where things happened fast as opposed to "monthly", and there was this sort of secret system with special words, activities, and achievements.