Friendly Robotics manufactuers robotic lawnmowers under the RoboMow brand name. On their website, they list several different models including: RL2000, RM510, RL855, RL555, and RM200.
The RL 850 is the older version of the current RL 855 and it is sold on Amazon.
From the Amazon page for RL 850:
The Husqvarna Automower is one of the most advanced robotic lawn mowers on the market. The NiMH battery powered mower is suitable for up to 3/4 of an acre and when it is out of power, it finds its own way back to the charging station!
The robotic mower is attached with an anti-theft alarm in case you're woreied about jealous neighbors picking it up and walking off with it.
The Black and Decker electric mower uses an electric cord for power (unlike other electric mowers that use a battery). The webpage for the mower notes that the farthest point in your yard that you will need to mow should not be more than 100' from the electrical outlet.
From the Amazon page for the MM1800 :
The Brill is manufactured by a German company that doesn't have a great web presence in the United States, so the product description below comes from the Amazon page for Brill Razorcut 33:
