Robotic vacuum for pet owner
We have a small apartment with wood floors and one cat. The iRobot Roomba 560 works well if we run it daily, but the bin needs to be emptied every couple of days, and the brushes need to be cleaned at least once a week.  With 3 cats, I imagine it may overwhelm the Roomba's capacity.

On the other hand, the new 700 series models have a higher capacity vacuum bin, and we just bought this new bin for the 560.  In theory this can hold more cat hair and the stronger motor sucks more of the hair off the brushes and into the bin.  We'll see over the next few days how much of a difference this makes...