It depends how deep you are into dreaming about "projects".
I've got a buddy who's been dreaming about inserting a .308 into the lower barrel of his over/under and using it as a do-all hunting package. He wants to be able to hunt grouse and deer with the same gun. He just hasn't come across a .308 barrel, yet. I have heard about doing this with old LeeEnfield barrels and single shot shotguns for a cheap and dirty hunting "rifle" for folks in the north. Get your outside dimensions turned to the right size, and make it a press fit with O-rings. Not a long range sniper rig, but it will send the bullet in the general direction, with some kind of accuracy.
Or, like Trevj said, sell it, or trade it, and get something you figure you can use more than a 30-30 barrel. There probably are people who truly do need a good barrel for one of their projects.