Survival knife, biotch! I'll go Killzone on their asses, and corkscrew it straight into their eye!
If there's more than one, there's always the Splinter Cell approach...Heh heh....
As for further improvised weaponry, I have: Vitamin bottle[footnote]If they were in/went in the kitchen area, I could spill it and make them slip, maybe.[/footnote], Glade spray[footnote]Like pepper spray, only it has a fresh scent! And I mean the stuff that simply burns like hell in the eyes...Not the corrosive sort. (I think...)[/footnote], various pens and pencils[footnote]Not quite as fun as stabbing them in the eye with the knife, but still works.[/footnote], a shelf full of books[footnote]None of them heavy, but all of them pointy, since they're square.[/footnote], and a Nerf gun[footnote]First, yes that's as weird as it may sound. Second, even if it is plastic, I'm sure a rifle butt to the face is still unpleasant.[/footnote].
I don't know about you, but I'd go with the Glade and knife.
Oh yeah, and an Airsoft G17. Orange cap removed, because the silencer broke, and took it with it when removed. Looks real. Also, it's intimidating, since it's 1:1 scale, and two-tone silver and matte black. Might choose knife for actual attacks, and Glock for sheer intimidation factor.
Tactical knife style.
I just hope the "thieves" don't turn out to just be the FBI...Or worse, the CIA. Again.