I like space and ALIEN aliens. -shrug- Made it interesting enough to read.Of course, the robot bodies can be non-humanoid shapes, too.
Gravity Manipulation. Of course, if someone manages to turn it off: *splash* *flop flop* *dramatic final words* *death*
EDIT: Yeah, saw your note just now about how true anti-gravity doesn't exist. But this is simply...changed IMPLIED gravity. It's more like magnetism, using the natural polar structure of water molecules to hold it together. Maybe it won't be as dramatic as levitating like in the picture. I can't think of an alternative explanation very well (it's 4:30 AM, and I've been awake for 3 hours).