Electric Toe-kick Heaters
Toe-kick heaters are ideal for limited space applications. They are designed to be very low profile, about 3.5" which allow them to fit nicely in a 4" toe space under cabinets and vanities. Their proportions allow the use of a motorized forced air fan to distribute warm air.
For best performance they should be used as a supplemental source of heat and have a remote line voltage thermostat, however most models also have the option of a built-in thermostat.