First miniature(s) you used.
The addition of miniatures into game has been a (relatively) recent addition to my gaming experience. My original group never used them. Yeah we would buy them occasionally and paint them, but we never used them with D&D. I didn't use minis until the end of the 3rd era (right before the release of Pathfinder). The first person I met that used minis regularly was my good friend Stew.
Stew is a minis fanatic. The pictures included below are a part of his collection. He has organized bins full of minis (also pictured). I am totally jealous. His collection is phenomenal. And he has Orcus... Recently he's been working on crafting his own terrain and dungeons, which look great.