A couple of weeks ago I bought a Roomba 531 robot vacuum cleaner from John Lewis with the idea of letting it do the vacuuming whilst we're at work.
This means that we can vacuum every day; and hopefully that will help my wife's asthma. This little device is *brilliant* - it does a better job than I do. We just press the button when we leave for work in the morning and whilst we're on the morning commute the robot is working away. It makes an excellent job of the edges. It has a side brush and detects the edge of the room, using the side brush to go right into the edges. It also goes under things - so under the TV cabinet, wardrobes, etc.. all gets a clean.
It won't fall down the stairs, thanks to sensors that find any drop in the surface level. There is also a 'dirt' sensor, so it concentrates more effort where it is really needed.
It even has a serial port, so you can access it from your computer. There are a lot of commands that can be used on the serial interface. How long will I be able to resist hacking the vacuum cleaner? Maybe I should get one of these Roomba USB boards on order...