That sounds as if there may be an electrical problem with surges or something. Anyone know more about this than I do? Do you have access to one of those little electrical testers?
I was an electrician years ago, and porch light bulbs even then didn't last as long where people let the door slam. We'd put rough service bulbs (thicker filament) in, and that would usually cure the problem. Or, just don't let the door slam. Same goes for any fixtures in the house that ate bulbs. Ran across a few bulb eating fixtures that were on the same circuit with a fridge or freezer with a motor that was about to go.