Even though this is a parody and not a real conspiracy I thought I'd share what I posted earlier. Copy/paste because it's long and i don't want to type it all out again.

Princess Leia was Luke's sister. She was just as powerful in the force as he was. She kept it a secret. She had a falling out with the people on Alederaan. After discovering her Jedi powers she learned the truth. She read the mind of her "father". She found out she was lied to her whole life by people claiming to be her real family. She used the force to find her real father Darth Vader. She allowed them to capture her. She used her force powers to make them go to Alderaan. She then used her powers to make Vader give the order to destroy the entire planet.

She then aided in the destruction of the Death Star to cover up any tracks left in the minds of those on board. You see when a Jedi uses his or her powers on you it leaves a trace. This trace is distinct for each Jedi. Had Vader been put on trial Leia's Jedi residual would have been seen. This residual can be put back together and seen by another Jedi. So she had the Death Star destroyed to be sure no one would ever know.