Brandon mentioned Water/ mineral/ oil/ and gas rights.

Scrubbing really nasty floor grout with white vinegar and a scrub brush removed the accumulation of oil and dirt that I feared would not come off.

If not (ie two full-time working spouses) your only other option is going into land conservation deals, solar deals, or oil and gas deals - all of which have some risks.Explained in a different way...1) There are ordinary/W2/active income on one side.

When I hear stories on BP of someone spending $25K on a RE program, or some snake oil salesman ripping someone off....

They were quick to bounce back.People invest in Bay Area and Manhattan for prestige, those oil sheiks dont care if the property cash flows or not.

Fine, the uses of that deed is proper in most jurisdictions, Texas does have some odd title carve out in title insurance, like not insuring mineral rights, but, whatever.You check and you see it was a divorce. 99.9% of novice examiners don't read the decree.Then the wife gets behind, the husband is still on the note, they go to foreclosure.There is a prior lien!

To insulate ductwork, there a various kinds of wrap insulation (from foil faced / bubble, to mineral wool or fibreglass blankets) or, if in a wall cavity, ceiling or bulkhead/soffit, you can simply pack mineral wool insulation around the ductwork.  

replace oil furnace with gas furnace with 3 zones/thermostats/loops/pumps - none of them 'slave' zones - that's what i'd do in philly

I pretty much break even w/ the house now........ after many up's and downs over the past ten years. one of my biggest setbacks is that i pay for the oil (underground tank) heat.  

@Jon Klaus $4.99It's an oiled wood, not a polyurethane finished product, giving it a matte finish.