One item i've found that i use pretty regularly is one of those little 'yougurt makers'. Basically, it is a tray with 5 indentations in it (about the size of the smaller Ball jars) with a lid that sits over the whole thing. The whole unit is thermostatically controlled at a temperature of about 80 degrees. The idea is you put some milk in the little jars, then add a little innoculation of yogurt, then you let it sit, and the yogurt will grow. Now, this also means you can put your jars in the yogurt maker, and the warmth (and the humidity maintaining/contaminant preventing lid) make for a dandy culturing area.

janitor