I collect and grow plants.
My main interest is the Nepenthes or Asian Pitcher Plant.
Every viable window in my house has them hanging in and around them, and the house is full of plants in general.
I have a large collection of Sarracenias (trumpet pitcher plants from North America) Dioneas (Venus Fly Traps) and Drosera (Sundews) outside as well as tons of orchids and cactus, including some exciting ones like Echinopsis pachinoides (San Pedro).
I also have a bunch of Amorphophallus, including the notorious Amorphophallus titanum (latin for giant mis-shapen penis) or "Rotting Corpse Plant" that is the world's largest unsupported infloressence when it eventually flowers.
But the main interest/collecting thing for me is the Nepenthes- I'm always hunting for them and shuffling them around in efforts to make room or trading them or giving them away as an excuse to get more.