steam boiler flue heat recovery options

I was wondering if there are options for productively using the ~250 degree exhaust from my oil boiler.

Are there any products that will exchange that heat with incoming air for the burner? Would that increase efficiency since the air wouldn't need to be heated?

Could the heat be used to augment our gas hot water heating?

Could the heat be exchanged for outside air, making that air warm, pressurizing the house with the warm air, and perhaps allowing for a tighter house or less air/heat leakage to the outside?

Thanks for any tips.

Cheers,

-David Laidlaw