I'd love to see this list as well. Could be a good guide for the aspiring collector. I'm by far not an expert and I am sure I'll leave some out but lets see...
US:
-1903 Springfield
-1903A3 rifle (*2)
-1903A4 sniper (*2)
-M1 Garand
-M1C sniper (*2)
-M1D sniper (*2)
(Note from JWarren: I don't think the M1D ever saw combat in WWII)
-M1 Carbine
-M1A1 Carbine (paratrooper) (*2)
-Thompson SMG (semi-auto reproduction count?)
-Colt 1911A1
-BAR (nasty expensive semi-auto reproduction available, but don't know if it would count)
-M3A1 Carbine (the Grease Gun, semi replicas available here and there) (*2)
-M1919A4 (*2)
-M1919A6 (*2)
-M1917 (*2)
-M1928 (*2)
-M2HB (semis available for all the belt-feds) (*2)
-US 1941 Johnson Semiautomtic rifle (*3)
-1917 Enfield (*4)
British:
-No4 enfield (*1)
-Sterling SMG (semi-auto reproduction available?)
-Webley Mk VI & IV revolvers (*5) and (*6)
-P14 & M1917 Enfields - Home Guard (*6)
-#1Mk3 Enfield - almost exclusively used at Dunkirk (*6)
-#5Mk1 Enfield - Jungle Carbine (*6)
-Enfield #2 various marks (*6)
German:
-K98 Mauser
-MP40 (dunno if a semi-auto/reproduction available or if counts)
-StG44/MP44 (semi-auto reproduction IS available, but not importable to US) (*5)
-Luger
-P38
-FG42 (I think someone is planning on making a gawd-aweful expensive repro)
-G41 (*1)
-G43/K43 (*1)
-Cz27 (*5)
Hi-Power (*5)
Japanese:
-Arisaka type 38 (*1)
-Arisaka type 99 (*1)
-Type 44 carbine, 1st, 2nd, and 3rd variants (*2)
-Type 38 rifle, carbine, and cavalry carbine (*2)
-Type 99 rifle and long rifle (early, late, and last ditch) (*2)
-Type 2 paratrooper (*2)
-Type 97 sniper (*2)
-Type 99 Naval special (*2)
-Type 99 sniper (*2)
Italian:
-Carcano (*2)
French:
-Mas 36 (*1)
-Lebel (*6)
-Berthier in colonies (*6)
Canadian:
-Long Branch No.4 Enfield (*1)
-Hi-Power (*5)
Australian:
-No1 Mk 3 enfield (*1)
Russian
-MN 91/30 (*1)
-MN m38 (*1)
-MN m44 (*1)
-SVT 38 (*1)
-SVT 40 (*1)
-DP ( semi auto repro) (*1)
-PpSH 43 (semi) (*1)
-ppsh 41 ( semi) (*1)
-T33 pistol (*1)
-M1895 revolver (*1)
Swiss
-K31 ( may not have seen combat, but still around) (*1)
-m94 (*4)
-m96 (*4)
Austrian
-Styer M95 (*1)
China
-Sheng kai shek Mausers ( available from Omega Weapon Systems!) (*1)
North China
-Type 19 (*2)
-Type I (*2)
Finnish:
Converted M91's (*4)
Mosin Nagants -M91, M24, M27, M28, M28/30 (
JWarren edit: I have this one! ), M39, M91/30 (*6)
-Lahti L35, Luger 1924, various Rubies, M95 Nagant Revolver (*6)
Key:
(*1) - credit: Hoppy590
(*2) - credit: Ian
(*3)- credit:michaelq83
(*4)- credit: jefnvk
(*5)- Eightball
(*6)- Ash
Please add anything to this list that you can think of, and add countries. I know I missed some.
-- John