Then there is "The Greatest Green Lantern of All" from 1972, which added an Oan dimension to Superman's origin. However, I see that it's already in the "Untold Tales of Krypton" section.
It is, but most of the "origin" stories that I've added to the "origins of superman" section already exist elsewhere on the site. This is just a common access point for all of them. It's hard to tell whether or not that story counts as a new "origin" or if it's a separate story that happens around the origin.
There is Superman: The Secret Years (1985?), a 4-issue miniseries that covers the time period that the 287 pages of Birthright missed. I highly recommend it, yet do not own it.
You say you don't own it - have you read it? To be honest, I think the Frank Miller covers are the best part.
But I do like it, and think it's a prime candidate for Graphic Novel compilation. It's been on my list to add to STTA for quite some time, but I'd also want to include all the back-up stories that lead into it. (attn DC: if you do a graphic novel, you should hunt down those lead-in back-up features too)
I'm sure that others will come to mind. I'm trying to think of a good 50s origin, but can't. However, there was this great miniseries in 1986 called Man of Steel.
Just Kidding.
We've got that covered - you must have missed the "1993" origin.
