When I cook bacon in a pan, I use what's left to cook eggs in it, but whatever is left over (or if I don't use the fat at all), I pour it in a mason jar next to my stove so the pan is easier to clean later.

So, what can I do with all of this now-somewhat-hardened grease that I've accumulated over time? Once in a while I will use it to grease my pan if all I'm making is eggs, but is there any other use for this jar of deliciousness?