The Sony, Microsoft, and McDonald Conspiracies:
conspiracies to rule the world. Sony appears to be in the lead here, although it is unclear as to who the ultimate victor will be.

The Pop-Star Conspiracy:
to create a legion of fans loyal to the death to one teen idol. This has failed repeatedly, but they continue to try.

The Shoe-Lace Conspiracy:
Set in place to make the U.S. dependant on shoe laces by making most shoes need them and making those shoes that don't use laces feel like you're stepping on some type of thin rope.

The Alien Conspiracy:
The aliens trying to keep the government from knowing about aliens from outer space: How do I know? I'd have to kill you if I told you.

The Nintendo Conspiracy, code named "Pokemon":
To brainwash the world's youth with subliminal messages in each toy it sells. In 20 years, Nintendo would control nearly 70% of the adult population. (They had predicted 80%, but German and British children seem to be rather resistant to their methods.)

The School Conspiracy:
To brainwash the children of America with poor literature, and worse cafeteria food, in order to make them think that atheletes are better than nerds. We all have to deal with this one. Fight on, fellow geeks!

Finally, the Pie Conspiracy:
By making pie irresistably funny and tasty at the same time, they are enslaving us with it. There may also be a Monkey Conspiracy similiar to this one, without the tasty part, but I have yet to look into it.