Servo
A Servo is a robot that was introduced in Livin' Large. It costs a whopping $15,000 Simoleons, but will walk around the house, cleaning up everything, as well as repairing broken items and gardening, so Sims don't have to. Servos can also make meals for your Sims, but they aren't very fulfilling.
When The Sims 2: Open for Business Expansion Pack came out, he returned with many upgrades including: complete control, relationships, female versions, being able to "WooHoo", having the needs of Power, Social, Fun, and Environment, ect.