Roo riding a floaty thing
A "floaty thing", as it was referred to by Raffaela Musiker, was a device that was similar to a skateboard, except that it was capable of hovering.
Raffaela told Seven of Nine that she had a premonition of them as an elderly couple sitting on a park bench and tripping teenagers on floaty things with their canes. (PIC: "Monsters")
Roo often rode on what appeared to be some sort of purple "floaty thing", and had matching goggles as well. When JR lost control of his rocket boots, she rode her hoverboard over to him and grabbed a hold of him to stabilize him so as to prevent an accident. He referred to her rescue as a "stellar save." Her hoverboard was apparently tapped into the transporter system, as her hoverboard and goggles immediately beamed away when she was finished using them, probably storing them in the pattern buffer. When it became apparent that an asteroid from the Bathnar Nebula was heading for their planet, JR ordered everyone to their stations, and Roo rode her hoverboard there.
Not long after that, she used her hoverboard again to take look at all the soap bubbles from the soap bar asteroid outside of their scout headquarters. When a targ ate one of the bubbles it somehow gave it the ability to float in the air. She zipped by on her hoverboard and grabbed the targ in mid-air and said "I think I'll call you Bubbles!" (SCO: "Asteroid Blasters, Part 1")
She used her hoverboard again when a meatball asteroid from the Noodle Nebula was about to collide with Earth: she rode it to her console station. (SCO: "Asteroid Blasters, Part 2")