I was recently complaining to a friend of mine about how much I love my Sig P220s but wish they made a double-stack .45.  He said he had seen one at a gun shop in Tennessee a while back and I told him he was crazy.  He swore up and down that he had seen a double-stack Sig P220 .45 but said the frame looked slightly different like it might have been some sort of custom.  
My friend is fairly gun-smart and I usually don't doubt him but I've never even heard of such a creature.  But I want one if anyone can tell me where to find one!

Been around a few European 220s, but never seen a double-stacked 220.

SIG apparently had a prototype called the P-221 which featured a double stacked magazine. I think it fell through due to size and weight.

http://www.thehighroad.org/showthread.php?t=258549

I'm leaning against a Taurus PT145 Pro that is a 10+1 (double stack) compact gun.  It's pretty darn slim and compact.  My P220R is what it is, but if they really wanted to they could do it, Taurus did.

Frankly, there are a lot of guns that are low capacity and I think they continue to exist because they are older yet legitimate designs.  I see 9mm guns with 8 shot or 10 shot mags.  Except for legal limitations (CA, etc.) it makes no sense to me.  My new 9mm is a P226R with 20rd mags.

Mo ammo!