Taking bonsai approaches to the next level, a Japanese company based out of Kyushu has raised over half a million dollars so far for its levitating (and rotating) tree system.
The fauna in question span quite a range, from flowering plants to pine trees to mosses. The magnetic levitation tech supports up to 250 grams of whatever species you prefer (up to a few inches in width), powered via a simple AC adapter.
Of course, you can further decorate your little floating worlds however you like, with ceramic figures, lava rocks or other scene-setting touches.
The system comes as a DIY kit priced starting at around $200, depending on whether you wish to get both the mechanical system and a starter plant or just the technology portion. There are also both modern and traditional-looking, hand-crafted bases, depending on your aesthetic preferences.