Check out most serials. George Lucas loves serials and they are greatly inspired from them. Two fisted heroes like Indy were common in serials, and Nazis were frequent villains, or other villians bent on world domination/evil dastardly plots. Ones I can think of off the top of my head that are especially close are:

Zorro's Fighting Legion-In ROTLA, the scene were Indy is trying to off the truck with the Nazis and ends up falling under it and climbs back up from a rope on the back was taken directly from here.

Dick Tracy- In Last Crusade, the boat chase, with Indy racing between two ships being pushed together came from here.

Some others that also have strongly Indy-like:

Perils of Nyoka (Nyoka and the Tigermen)

The Tiger Woman (Perils of the Darkest Jungle)

King of the Royal Mounted

Spy Smasher

G-Men vs. The Black Dragon

Secret Service in Darkest Africa (Manhunt in the African Jungle)