Battlestar Galactica executive producer Ron Moore has been discussing last week's series finale with fans on the BSG forum, where he dropped an interesting tidbit about an ending that might have been.
In this version of the story, the Galactica herself ends up on Earth instead of being flown into the sun, and she also manages to show up in our present-day timeline:
"There was a point in the development process where we discussed the idea of the Galactica not being destroyed, but having somehow landed on the surface more or less intact, but unable to ever get into orbit again (the particulars here were never worked out, so don't ask how she made it down without being torn apart). We talked about them basically abandoning the ship and moving out into the world.
"Cut to the present-day in Central America where there are these enormous mysterious mounds that archeologists have not been able to understand (it may have been South America, I can't recall the exact location, but these mounds really do exist). Someone is doing a new kind of survey of the mounds with some kind of ground-penetrating radar or something and lo and behold, we see the outlines of the Galactica still buried under the surface."
Moore said they ultimately didn't go with the ending because they wouldn't have been able to reconcile it with the "reality" of the series.
"It was an intriguing idea and we bandied it about for a while, but ultimately rejected it as a little too cute and also felt that it would violate our contemporary reality, in essence 'branching off' the BSG story in 2009 into an parallel reality where a battlestar was discovered in Central America. I wanted the end of the show to directly relate to us, not to a world where that event had occurred."