Magnetic stirrer hot plates.
These are for ideal use in the science laboratory.
(Excerpt taken from Wikipedia:)
A heating element, whose power may range from a few hundred to a few thousand watts, can also be incorporated to the stirrer to allow the reaction flask to be heated and stirred at the same time. The maximum reachable fluid temperature depends on the size of the flask, the quantity of solution to be heated, and the power of the heating element.
Because of its small size, a stirring bar is more easily cleaned and sterilized than other stirring devices. They do not require lubricants which could contaminate the reaction vessel and the product. Magnetic stirrers may also include a hot plate or some other means for heating the liquid.
A stir bar retriever is a separate magnet on the end of a long stick (usually coated with PTFE) which can be used to remove stir bars from a vessel.
For Stirrers, click here