On Thu, 18 Sep 2008 22:23:52 -0700, Square Peg wrote:
Most coffee mug warmers are under-powered. One reviewer on Amazon said
that they were restricted to about 24 watts by law.

This one

http://www.amazon.com/Bunn-BCW-Warme...1796737&sr=8-3

is made for warming the whole coffee pot. It says it's 120V/15amp.
Several of the reviews say that they use it for a single cup, but it
keeps it too hot. It only has on/off -- no temperature control.

Can I put it on a 300 watt dimmer switch like this?

http://www.amazon.com/Lutron-Electro...1799800&sr=8-2

If not, is there a way to ramp the the power down as an external
thermostat?

I don't know where that 120V/15A spec came from. Bunn says nothing about
the requirements of the BCW.
Two other heavier duty warmers on the product page have 100W elements.

http://www.bunnomatic.com/retail/parts/warmer.html