Ran across this thread while looking for something else...

Anyway, here goes (in no particular order) -

Papaya King - 86th & 3rd NYC
Gray's Papaya - 72nd & B'way NYC
Walter's - Mamaroneck, NY
Roscoe's - Hartford, Ct.
Varsity - (previously mentioned)
Pink's - (previously mentioned)
Nathan's - (previously mentioned)
Zweigle's (both red hots (Beef); white hots (Pork) - They swear by them in the Rochester, NY area - only kind available in hot dog joints there
Harvey's - Montreal and Kingston, Canada
Shopsy's - Toronto, Canada
Dodger Dogs - LA