The largely recession-proof Markel Corp. has been on a buying spree of late, gobbling up all manner of bizarre businesses, from burrito-folding-machine makers to college-dorm-furniture outfits. The $2 billion specialty insurer, run by the Markels and chief executive Alan Kirshner, has a sophisticated investment guru in Tom Gaynor, a Warren Buffet understudy. Markel also dabbles in real estate, recently acquiring a 50-percent stake in West Broad Village. Its partnership with local developer Justin French, who threatens to let his Markel-funded properties default, could cost the company a few million. Note to French: Flipping off the Markels won't help your credit rating.