Lucas “appropriated” bits from a lot of sources for Star Wars. It was done, I think deliberately, and part of the fun is finding out where items came from.
– As as already been mentioned, he took some of the plot, and the characters of Han Solo, Princess Leia, and R2D2 and C-3PO from Akira Kurasawa’s The Hidden Fortress. Lucas has admitted to this.
– Darth Vader’s costume is essentially that of Doctor Doom from The Fantastic Four comic book, but topped off with a samurai helmet (another homage to Kurasawa, I guess).
– As I’ve explained at length, the ending is lifted, dialogue and all, from The Dam Busters http://www.teemings.com/issue03/force.html
– The opening title “crawl” vanishing into the distance is taken directly from several of the 1940s serials. The whole atmosphere, in fact, resembles those serials (as does the feel of the Indiana Jones movies).
– The culture of the spaceports and the gathering of aliens was a staple of science fiction of the 1940s and 1950s (and, to some degree, the comic books of the 1960s). Look at the bar scene in Delaney’s Babel - 17, or Catherine L. Moore’s stories of Northwest Smith (shades of Indiana Jones!), where pioneering spacefarers were modeled on pioneers on earth.
– The skeleton in the baxckground of C-3P0]s wanderings at the beginning of SW looks like a sandworm from Dune.
What really made Lucas’ filmd attractive was the way they played all of this with a straight face and to the hilt. They really immersed you in the Star Wars universe, filling it with so much believable detail that you wanted to be there. (The two suns of the Tatooine sunset and the high-tech binoculars with their complex readouts didn’t * have* to be there – they’re tiotally irrelevant to the plot. But they create an undeniable mood and sense of otherworldliness. On the other hand, it’s a comfortable other world. Undle Owen and Aunt Beroo use food processors and don’t eat, say, live rats. They live underground, but in comfortable digs Sorry). The alien band in the Bar plays what sounds like Big Band music, not Krel Instrumentals.