OK, have been pondering...
The phrase "This has happened before and will happen again" pops up alot in the series.
The 13th tribe made its way to earth. Along the way there is "the temple of the five"
What if the 13th tribe are cylons? This has happened before and will happen again...
That could explain why there is a temple of five on the algae planet.
What if the reason Kara Thrace is the harbinger of death for humanity is because when she leads humanity to earth it turns out that the people already there are actually Cylons or Human/Cylon hybrids from thousand(s) years ago.
This also could explain why the final five are suppost to have been to earth and know the way.
Just some random thoughts I have had. Probably totaly wrong, but I ponder when there are no new episodes to watch for a week...