I am a great fan of Hotbeds because it's like using cheap underfloor heating to heat up a growing medium, (usually compost), when the outside temperature is really cold.
It is relatively cheap as it uses a mixture of fresh manure, (less than 6 weeks old), and straw which can usually be free to collect. Yes, it takes a bit of effort in collecting, but I feel it's well worth doing to take advantage of increasing daylength light levels while keeping early frosts at bay.
There's more information and some videos about Hotbeds on my Links page.
Potatoes in Pots, Salad Lettuce, Chives, Pea Shoots and some early seed sowing sitting on the hotbed taking advantage of the 'bottom heat'