are there any guns made specifically for left handed shooters?  or what about aftermarket parts to make a right handed gun left handed? 

Savage makes left-handed bolt rifles.  Taurus and Winchester make pump-action rifles that are top-eject, and so suitable for either hand.  Ithaca shotguns are bottom-eject, and so not hand-specific.  The Beretta Storm has ejection ports on both sides, and you can swap the bolt and action handle for either left or right handed operation.

Left-handed handguns are an oddity, though.  There are a few bolt-action target pistols that are made in both right and left handed versions.  Never seen or hear of a left-handed revolver.  Many semi-autos have optional or after-market ambidextrous controls.

Stag has AR15's designed for left handed shooters.  The ejection port has been milled on the left side of the upper receiver as to not throw brass in the shooters face.  However i am nor sure about the administrative controls such as the bolt release, forward assist, etc.

It looks like there are quite a few options out there. The Robinson Arms XCR, FN SCAR, Bushmaster ACR are all ambidextrous if you are looking for a semi-auto. Savage, Remington, Ruger all make left handed models.

Check this out, it looks like Buds Gun Shop has a whole southpaw section. Pretty cool.