So I'm trying to compile a list of ambidextrous or Lefty Friendly Weapons. Please feel free to contribute anything useful.
Pistols: (I actually prefer the RH mag release, use index finger. Slide releases usually suck though)
Smith & Wesson M&P
Taurus (most models)
Beretta 92 +variants
Some 1911
Walther p22
Glock
Springfield XD
Charter Arms Southpaw .38Special(only

CZ 85 (Ambi version of the CZ 75)
Zastava EZ (Sig reminiscent, but Ambidextrous)
Sig Sauer (Normally not Lefty friendly, but there is a gunsmith conversion available)
Bersa Thunder series
Rifles: (I also prefer the RH action on bolt guns)
Ak platform [Demonstration] (arguably easier for a lefty, due to charging handle and safety lever locations)
AR-15 with optional ambidextrous controls
FN F-2000 series (forward/downward ejection)
FN P-90 (downward ejection)
Beretta Cx4 carbine (reversible ejection port, ambi controls)
Keltec sub2000 (Ambi charging handle)
Kel-tec RFB (forward ejection)
MSAR STG-556 (reversible ejection)
Stag Arms LH AR15
Shotguns:
Mossberg 500/590 (Slide release is more accessible with LH grip for me, safety is ambi. (awkward with a pistolgrip though))
Winchester 1300?
Remington 870 Left-handed model
Bring em on!
EDIT for typo's and glaring mistake. Also to update the list.