According to Wikipedia, still-life is defined as photography depicting mostly inanimate subject matter, typically commonplace objects which may be either natural or man-made.
My still-life often involves intricate plans, hard-to-find props and strong subject matter, often sharp or deadly items, items that provoke a strong emotional response. I also like old worn-out things, novelties that have seen the world and have been used by someone or had several owners in their past lives. Sometimes I just enjoy seeing a group of items together for no apparent reason.